Modeling of Olsen cycle for pyroelectric energy harvesting and assessment of abnormal electrocaloric effect in ferroelectric single crystals G. Taxil, [START_REF] Livermore | U.s. energy flow trends -2012[END_REF][START_REF] Mckinley | Thermomechanical Energy Conversion Using Ferroelectric Materials[END_REF][START_REF] Sultana | [END_REF]4 M. Lallart, 1 B. Ducharne, 1, 2 T. T. Nguyen, [START_REF] Mckinley | Thermomechanical Energy Conversion Using Ferroelectric Materials[END_REF]4 H. Kuwano, [START_REF] Mckinley | Thermomechanical Energy Conversion Using Ferroelectric Materials[END_REF]4 T. Ono, [START_REF] Sultana | [END_REF] and G. Sebald 1, 2 1) Univ. Lyon, INSA-Lyon, LGEF EA682, F-69621, France.

2) ELyTMaX IRL 3757, CNRS, Univ. Lyon, INSA Lyon, Centrale Lyon, Université Claude Bernard Lyon 1, Tohoku University, Sendai, Japan.

3) Graduate School of Engineering, Tohoku University, Sendai 9808579, Japan. 4) New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aramaki-Aoba, Aoba-ku Sendai, Miyagi 980-8579, Japan.

(*Electronic mail: mickael.lallart@insa-lyon.fr) (*Electronic mail: gaspard.taxil@insa-lyon.fr) (Dated: 2 November 2022)

The energy conversion potential of ferroelectric materials originating from their phase transitions in particular temperature ranges and electric field values is very promising. Pyroelectric energy harvesting consists in directly converting thermal energy into electrical one. Due to its high energy conversion potential, the Olsen cycle is the most favorable for pyroelectric energy harvesting. This cycle includes two isothermal and two constant electric field branches. In this study, the Olsen cycle was modeled, then varying temperatures and applied electric field directions for different crystal orientations were simulated. Polarization responses were obtained via the Landau-Devonshire theory. Then, an innovative way to model the electrocaloric effect was proposed; experimental results and first-principle calculations confirmed the simulation results. The resulting negative electrocaloric effect due to crystal orientation, previously reported in the literature, has been successfully simulated through a phenomenological approach. Finally, we identified which phase transitions are interesting for pyroelectric energy harvesting applications depending on crystal orientations while obtaining an energy density in the order of ≈ 10 2 mJ/cm 3 . This value corresponds to previous results in the literature.

I. INTRODUCTION

Energy harvesting from residual energy in the environment is a promising way to power wireless sensors or other lowpower devices in harsh or remote conditions. The advantages of this method are the low cost and the absence of maintenance like replacement of batteries (for instance due to their self-discharge). There has been thus a significant growth of studies in energy harvesting in the last decades due to the spread of the "Internet of Things" (IoT), which implies the connection of many low-powered connected devices autonomously exchanging data. There are several types of energies in the environment that can be converted into electrical energy, for instance vibration, solar radiation, wind and waste heat. Waste heat is an underestimated energy source seldomly exploited. Approximately two-thirds of the energy produced in the U.S is rejected as wasted heat [START_REF] Livermore | U.s. energy flow trends -2012[END_REF] . There are numerous heat sources where energy is produced, including power plants and oil refineries. Other heat sources in daily life are available, including hot water and exhaust pipes. Other growing activities such as the heat dissipated from data centers and solar panels are exciting sources for thermal energy harvesting [START_REF] Mckinley | Thermomechanical Energy Conversion Using Ferroelectric Materials[END_REF] . Another example is the heat dissipated by the human body [START_REF] Sultana | [END_REF] or the thermal gradient generated by solar radiations 4 which was used for pyroelectric energy harvesting. The energy challenges of the next decades have increased the interest in waste-heat energy harvesting and different approaches have been developed to take advantage of these energy losses with pyroelectric materials 5 . As for any energy source, one of the significant issues in heat energy harvesting is the low output power. Different methods exist to improve it, like the design of innovative electrical circuits 6,7 .The possibility of working on the electromechanical structure with different geometries can also be envisaged 8,9 . Another option is to exploit the phase transitions of ferroelectric materials, but very few studies were dedicated to this approach for energy harvesting 10,11 .

Ferroelectric materials are of great interest for a panel of applications such as wireless sensors, memories, transducers and so on. Their capability to convert vibration and temperature into an electrical signal (and conversely) is the most attractive feature of these materials. One of their remarkable properties is also their successive phase transitions either with temperature, applied stress or electric field. While very few studies proposed to take advantage of such transitions, this work aims at using them for energy harvesting purpose. As a first step, the work reported here proposes a thermodynamic phenomenological approach to describe such phase transitions. One significant advantage in using phase transitions in ferroelectric materials is to take benefit of the non-linear response of the polarization close to the transition and thus, increase the polarization variation. The main ferroelectric material used for such an application and studied both theoretically and experimentally is the perovskite structure ABO 3 . In the perovskite structure the ferroelectric distorsion gives a relative displacement of the cation with respect to the anion which induces a net polarization. Some perovskite structures such as BaTiO 3 , KNbO 3 (KNO) and KTa x Nb 1-x O 3 (KTN) undergo three phase transitions from rhombohedral to orthorhombic, from orthorhombic to tetragonal and from tetragonal to cubic with temperature (the symmetry of the crystal increases with temperature), pressure or electric field. The mechanism of phase transitions is very complex and only few theories allow describe them. Among them, the renormalization group works very well but is very complex in its formalism 12 . An easier way relies on the mean-field approximation. However, close to the transitions, this approximation fails to describe properly experimental observations. Hopefully in ferroelectric materials, the nature of the transition allows describing them in the frame of Landau theory (mean field approximation) due to their long-range interactions [START_REF] Rabe | Physics of Ferroelectrics: A Modern Perspective[END_REF] . For ferroelectrics, Devonshire used in the 1950's the Landau theory to describe the phase transitions of barium titanate [START_REF] Devonshire | Xcvi. theory of barium titanate[END_REF] . This theory is known as Landau-Devonshire theory and consists of developing the free energy term in power expansion of an order parameter which is the polarization in the case of a ferroelectric materials. In this context, the presents work proposes a comparative study of different ferroelectric materials with perovskite structure for pyroelectric energy harvesting. In a first step, the study will focus on the Olsen cycle and its description. Then, the theoretical approach for different crystal orientations with the Landau-Devonshire theory is explained. After that, the experimental confirmation of the modeling is made with analogy between harvested energy and the electrocaloric effect for different crystallographic orientations of PMN-30PT and BaTiO 3 .

Finally, the best phase transitions of ferroelectric materials for energy harvesting depending on crystal orientations are identified.

II. OLSEN'S CYCLE

Pyroelectric energy harvesting generally uses closed thermodynamic cycles to reach more energy output. Pyroelectric energy harvesting implies thermodynamic cycles in the polarization-electric field space, and in the entropytemperature space. We can consider the polarization P as the conjugated variable of the electric field E because of the high relative dielectric permittivity ε r >> 1 for pyro-electrics. Different cycles have been used for pyroelectric energy harvesting [START_REF] Olsen | [END_REF] . We can quote the Stirling cycle which consists of two isothermal and two constant electric induction processes. Another promising cycle is called the Olsen cycle and it is the one we choose to model here due to its high energy conversion capabilities. The Olsen cycle [START_REF] Olsen | [END_REF] consists of two isothermal and two constant electric field processes. The cycle starts from a low temperature T l and an initial electric field E i . An electric field is applied until a final value E f (A-B path on Fig. 1(a)). Then, the temperature is increased to a higher value T h (B-C path). Afterwards, the electric field is decreased to its initial value E i (C-D path). Finally, the temperature is decreased down to the initial T l value (D-A path). Previous studies have demonstrated the feasibility and possible future applications of pyroelectric energy harvesting via Olsen cycles 16,17 as waste-heat energy harvesting is a probable hot upcoming topic. In particular, Hanrahan et al 16 realized Olsen cycles with a laser-based pyroelectric harvester with a square temperature variation and a triangle function evolution of the electric field. We decided to use this temporal profile in our simulation for preliminary comparison purposes and model assessment. An illustration of the evolution of the temperature and the electric field in our theoretical approach is given in Fig. 4(b). It can be noted that the choice of the functions in a real experiment impacts the output energy 18 . However, the evolution of the temperature and the electric field was not crucial in our modeling as long as the changes in thermodynamic state were successive. Indeed, as we applied a positive electric field, we only considered the positive solution of polarization of the free energy. Moreover, the Landau-Devonshire theory is independent of time and all thermodynamic changes are thermodynamically reversible. The model did not consider hysteresis and the frequency dependence of the material due to the underlying assumptions. The modeling represented a single Olsen cycle over a single ferroelectric domain independently of its size. Further work could be devoted to assessing the effect of waveforms and frequency on the polarization and energy harvesting density. An electrical charge-discharge losses term added to the output energy was proposed by Smith et al 19 . Another possibility will be to use time-dependent Ginzburg-Landau (TDGL) model.

Energy harvesting can be more efficient if the thermodynamic conditions of the desired device are well established. Some studies aimed at improving the harvested energy by using phase transitions via modeling by phenomenological approach 19,20 . However, none of them made an investigation on using FE-FE phase transitions depending on the crystal orientation and the thermodynamic conditions. Here, we propose the optimum thermodynamic conditions for different ferroelectric crystals to perform Olsen's cycle with the help of such transitions. We decided to study different materials with temperature variation and electric field easily achievable for realistic applicative. The temperature variation T h -T l has been chosen to be 10K as it is possible to have such a temperature variation in a short amount of time 21 . The electric field variation was set to E i = 0kV /mm and E f = 2kV /mm. For studying energy harvesting in the frame of a thermodynamic approach, we modeled the thermodynamic path to represent the ideal energy harvesting cycle with Landau-Devonshire theory. The spontaneous polarization is obtained for each value of temperature and electric field and thus, the Olsen cycle can be obtained in the P-E space. An illustration of the Olsen cycle is presented on Fig. 1(a). The harvested energy is given by the hatched area of the P(E) cycle on Fig. 1(a) and can be expressed as:

W h = P(E)dE (1)

III. MODEL

The Landau-Devonshire theory has been frequently investigated in for ferroelectrics but significantly less for energy harvesting purposes. In this work, we propose to study thermodynamic cycles and ferroelectric phase diagrams through the Landau theory for various ferroelectric materials and orientations. In the Landau-Devonshire theory, the free energy is developed as a function of an order parameter and must be symmetric by a point group of a reference phase. All the other terms that are added to the free energy (generally called second order parameters) must be also invariant by symmetry of the parent phase which is the m3m (cubic) symmetry in our case 22,23 . The free energy is expressed as: F lgd = F 0 + α i j P i P j + α i jkl P i P j P k P l + α i jklmn P i P j P k P l P m P n +α i jklmnop P i P j P k P l P m P n P o P p + ...

(2) where P i is the spontaneous polarization in the cubic basis; α i j , α i jkl , α i jklmn and α i jklmnop are tensors which represent the different orders of the dielectric stiffness and F 0 is the energy of the cubic phase (set to zero). In our study, only α i j is temperature dependent and has a different expression depending on the studied material 24,25 . The different expressions are:

α i j = C * [coth( T s T ) -coth( T s T c )] (3)
and

α i j = C * (T -T c ) (4)
where C is a constant, T c is the Curie temperature and T s is the saturation temperature. The dependence of α i j with T s makes it possible to describe the quantum effects that appear when T is less than T s 26 . Unfortunately, finding this parameter for some ferroelectric perovskites is quite complex.

The total free energy for ferroelectric materials can be expressed as:

F = F lgd + F elas + F elec + F grad (5)
F elas and F grad respectively represent the contribution to the free energy of an external stress and the different possible domains orientations of ferroelectric materials. Ginzburg first introduced the latter in the case of superconductivity [START_REF] Ginzburg | On the theory of superconductivity[END_REF] . In this study, we neglected these two terms as the crystal is in a stress-free condition, and a single crystal under a sufficient electric field can be considered in a single domain state [START_REF] Chandra | A landau primer for ferroelectrics[END_REF] . Finally, only F lgd and F elec associated with the energy of an applied electric field have been considered. Under an external electric field, it is easier to express the energy in terms of free enthalpy variations instead of the free energy using the following equation (Legendre transformation):

∆G(P, T, E) = F lgd -E i P i (6)
With respect to the cubic O h symmetry, the free enthalpy becomes: By minimizing the free energy with respect to the polarization, we can find for each value of temperature and electric field the stable phase of the ferroelectric material and the associated polarizations. In our study, we consider four phases for each material. All the different ferroelectric states and polarization configurations are highlighted on Table I and are represented on Fig. 2.

∆G = α 1 (P
V.m.C -1 ×[coth( T s T ) -coth( T s T c )] ×(T -T c ) ×(T -T c ) α 11 -1.
The approach consisted in modeling thermodynamic cycles and to choose different values of low-temperature at which the cycle is started. We can identify the ideal zone for energy harvesting with variations of the initial temperature T l . The main goal here is to use phase transition to increase the energy density. We choose to study BaTiO 3 , PZN-4.5PT and PMN-30PT because they are one of the most studied ferroelectrics and there are a lot of available sets of Landau coefficients in the literature. Table II lists the Landau coefficients extracted from the literature for all the ferroelectric materials studied in this work. Depending on the crystal orientation, different ferroelectric phase transitions can be interesting. We choose here to consider the <001>,<011> and <111> crystallographic orientations. The electric field is applied along the cut direction as illustrated on Fig. 3. The free energy symmetry transformation is not necessary for <011> and <111> crystal orientation. In practice, the polarization is measured by the current variation flowing through the electrodes deposed on the faces in the electric field direction. Thus, the measured polarization is a projection of the polarization vector along the electric field direction. We therefore just changed the basis of the polarization vector 33,34 via a matrix rotation to this end. The polarization P' is defined in the basis of the laboratory reference frame (x , y , z ) and the polarization P is defined in the cubic coordinate system (x, y, z), yielding:

P i = A i j P j (8)
A <001> i j =   1 0 0 0 1 0 0 0 1   A <011> i j =    1 0 0 0 1 √ 2 -1 √ 2 0 1 √ 2 1 √ 2    A <111> i j =    1 √ 2 -1 √ 2 0 1 √ 6 1 √ 6 -2 √ 6 1 √ 3 1 √ 3 1 √ 3    (9)
We assume that the electric field is along the z' axis. Thus, we can define the unit vector z 001 , z 011 and z 111 and we can keep using the cubic (m3m) symmetry free energy. The polarization along the crystal z' axis for different orientations is thus given by:

P <001> 3 = P. z 001 ( 10
)
P <011> 3 = P. z 011 ( 11
)
P <111> 3 = P. z 111 (12)
with respectively z 001 = (0, 0, 1),

z 011 = (0, 1 √ 2 , 1 √ 2 ) and z 111 = ( 1 √ 3 , 1 √ 3 , 1 √ 3 )

IV. ELECTROCALORIC EFFECT

In order to validate our approach, the electrocaloric effect of PMN-30PT and BaTiO 3 in different crystallographic orientations is assessed to different litterature [35][36][37][38] . The electrocaloric effect is the ability of a material to change temperature when an electric field is applied. It is usually considered as the converse effect of pyroelectricity. We propose here to obtain the temperature variation via the converted energy in order to confirm the phenomenological approach to model Olsen cycle. Assuming the Maxwell relation

( ∂ P ∂ T ) E = ( ∂ S ∂ E ) T .
It is possible to express the heat flow of the electrocaloric effect Q ECE as:

Q ECE = T h E f E i pdE ( 13
)
where p is the pyroelectric coefficient The converted energy can be expressed depending on the pyroelectric coefficient as:

W h = -(T h -T l ) E f E i pdE (14)
If we substitute equation ( 14) in equation ( 13) the converted energy yields:

W h = -η carnot Q ECE ( 15
)
where

η carnot = T h -T l T h
is the Carnot's efficiency. Finally we can express the temperature difference of the electrocaloric effect as:

∆T ECE = W h η carnot ρc p ( 16
)
where ρ is the density of the material and c the specific heat. We can note that this equivalence depends on the temperature variation T h -T l . As we set this difference to 10K, it is a range of temperature where it is possible to linearize the pyroelectric coefficient and express the converted energy W h as a function of the heat flow Q ECE 32 . This approximation provides a good trend for the electrocaloric effect. However, this approximation does not give a reliable absolute value of the temperature variation of the electrocaloric effect because it depends on the chosen temperature variation T h -T l . This still allows validating the Landau Devonshire approach to model energy harvesting for different crystallographic orientations. In fact, the most important in the scope of this study is the trend and the relative temperature variation obtained with the phenomenological approach, which are in good agreement with experimental results.

Marathe et al 36 used first principle calculation for modeling the electrocaloric effect and performed experimental measurement with different crystallographic orientation on barium titanate. Our results shown in Figs. 4 and5 agreed with both experiments and first principle calculations. Especially, a negative temperature variation occurs for BaTiO 3 in the <001> direction at the O-T transition at 270K as shown in Fig. 4(a). Moreover, the <001> cut orientation will also induce a more significant temperature variation for barium titanate at the T-C transition compared to the other orientations. This behavior also agrees with experimental and first principle modeling and gives a good order of temperature variation for the electrocaloric effect 36,39 .

The results obtained on the PMN-30PT also agree with experiments performed on different orientations 38,40,41 . In fact, the <001> cut crystals still present a negative temperature variation but this time for the R-T transition which occurs approximately at 360K for PMN-30PT as shown in Fig. 5(a). These negative electrocaloric effects are due to the polarization that increases with temperature ( ∂ P ∂ T > 0). This phenomenon appears for specific FE-FE transitions in particular orientations. Compared to BaTiO 3 , it is the <111> orientation for PMN-30PT that provides better temperature variations at the T-C transition. This result was already observed in the literature 38,42 , thus giving an experimental confirmation of the phenomenological approach in the small temperature variation regime. Particularly, it predicts which FE-FE presents negative or positive peak in particular crystal orientation for specific phase transition of ferroelectric materials. These results therefore explain negative electrocaloric effect due to crystal orientation with Landau-Devonshire theory.

Both materials had an electrocaloric temperature variation which evolves monotonously with increasing electric field. Also, the electric field shifts the temperature of the peak. This temperature shift could be positive or negative depending on both crystal orientation and applied electric field direction. It can be observed that negative electrocaloric peaks associated with FE-FE transitions shift negatively with temperature for <001> orientation of BaTiO 3 and PMN-30PT in Fig. 4(a) and Fig. 5(a). These transitions correspond respectively to the O-T and the R-T transition. The positive electrocaloric peaks, on the contrary, are associated with a positive temperature shift with an increasing electric field for all FE-FE transitions of <011> and <111> crystal orientation, as shown in Fig. 4(d) and Fig. 5(d). Moreover, all orientations have a positive shift for electrocaloric peaks associated with the T-C transition. This behavior is due to the electric field, which favors the ferroelectric phase energetically compared to the paraelectric one. Another feature of both materials is a wider maximum peak when the electric field is smaller. This phenomenon can be well observed in Fig. 5(a) on the R-T transition at 370K. This result originates from the equivalence made between the harvested energy and the electrocaloric effect and has no real significance for the electrocaloric effect. This emphasizes the limitation of the approximation of equation ( 15) as an arbitrary temperature variation needed to be fixed for the Olsen cycle (10K here).

V. ENERGY HARVESTING

This section is devoted to the simulation method and the comparison of the Olsen cycle predicted and measured harvested energy. We will still consider PMN-30PT and BaTiO 3 with the three orientations detailed before. We choose to model the harvested energy as a function of the low temperature T l while keeping a temperature span of ∆T = T h -T l = 10K, E i = 0kV /cm and E f = 2kV /mm (Fig. 6(a),(d) and (g) and Fig. 7(a),(d) and (g)). These settings allows selecting the best working temperature range to improve the output energy of pyroelectric materials via phase transitions. We identified different typical values of energy that we denote with different numbers. These numbers are associated with thermodynamic cycles represented in a T-E phase diagram in Fig. 6(b),(e) and (h) and Fig. 7(b),(e) and (h). We also represented the associated cycles in the P-E space in Fig. 6(c),(f) and (i) and Fig. 7(c),(f) and(i).

The PMN-30PT in the <001> orientation depicted in Fig. 6(a),(b) and (c). A negative energy peak arises at T l = 346K for cycle n°1. This negative peek is associated with the R-T transition which occurs during the temperature variation at a constant electric field of E f = 2kV /mm. When we decrease the electric field, the material returns to its initial rhombohedral state. These different phase transitions result in an anticlockwise cycle in the high electric field region. Hence, this yields an energy loss or a minimal harvested energy in practical conditions.

For the <011> orientation of PMN-30PT in Fig. 6(d),(e) and (f), cycle n°1 also presents a negative peak at T l = 360K. This negative peak is due to the R-O transition. This transition happens during the heating in the isoelectric process and induces an increase of polarization due to the orthorhombic state favorable orientation. As for PMN-30PT <001>, we still have an anticlockwise cycle in the high electric field region. However, this energy loss is compensated by an energy gain in the low electric field region due to successive O-R and R-T transitions.

In the <111> orientation (Fig. 6(g),(h) and (i)), we have a positive energy peak at T l = 366K which corresponds to a temperature slightly lower than the R-T temperature transition at E i = 0kV /mm. Cycle n°1 is fully clockwise compared to the orientations. The harvested energy arises due to the occurence of the R-T transition at the high temperature T h when we release the electric field. This transition induces a fast polarization decrease. Hence, the area of the cycle is increased and therefore, energy is effectively harvested. During the cooling of the material, the <111> PMN-30PT transits back to the rhombohedral structure.

For all the PMN-30PT different orientations, cycle n°2 is the most interesting in terms of energy gain and of course made profit of the T-C transition due to the larger polarization variation at the Curie temperature. In all cases, it is always better to start the cycle with T l being close to the Curie temperature T c . Performing the cycle at T l just before the Curie temperature increases the area of the thermodynamic cycle. It is the < 111 > orientation which gives the highest harvested energy compared to the others. This is due to the T-C transition that occurs at a higher value of electric field for the <111> orientation. It is noteworthy that the <001> orientation has the highest value of polarization for the tetragonal phase. We would thus expect it to be the best orientation to work at T c as it is possible to have larger polarization variations. However, it is the one who gave the less energy output. This is due to the significant shift of the Curie temperature T c with the electric field maintaining a ferroelectric state at high temperature and small electric field. Barium titanate exhibits different results. In <001> orientation (Fig. 7 For barium titanate, the Curie temperature region also remains the most interesting region to exploit for pyroelectric energy harvesting purpose. Cycle n°3 for the <001> and <111> orientations exhibits an energy density of 190mJ/cm 3 whereas for the <011> the value is almost 220mJ/cm [START_REF] Sultana | [END_REF] . As for the PMN-30PT, for all orientations the energy peak n°3 is located at a temperature T l just before T c . For the <001> orientation, the polarization variation is more important but the Curie temperature shifts more with respect to the electric field compared to other orientations. The fact that ∂ T c ∂ E is more important for the <001> oriented crystal does not allow the T-C transition to occur during the heating in the isoelectric process for a temperature variation of T h -T l = 10K. The transition appears only when we release the electric field whereas for the <011> and <111> orientations, the FE-PA happens during heating but the polarization variation is smaller. So the area of the cycle, and thus the harvested energy, is a trade-off between favorable crystal orientation and Curie temperature shift, the best being a <001> ferroelectric oriented crystal with a weak Curie temperature shift. Additionally, we can note that when the temperature of a FE-FE transition shift positively with the electric field, then the energy density is positive and favors energy harvesting. On the contrary, when this shift is negative, the energy density is negative, leading to an unfavorable temperature window for pyroelectric energy harvesting. Fig. 8 displays a summary of the optimum phase transitions for pyroelectric energy harvesting with respect to their crystal orientations. To compare our model with experimental results, a plot of the harvested energy depending on the temperature variation is proposed on Fig. 9. In this comparison, T l is set to be constant at 373K. The experiment was performed by Khodayari et al 43 One can notice that the harvested energy predicted by the model is close to the measured one. The trend of the curve is also fine. A fast increase of the energy occurs for ∆T = 60K in both curves due to the T-C transition. However, the fitting is not perfect and these differences can be explained by the presence of Polar Nano Regions (PNRs) especially in the high temperature region close to the Burns temperature. These PNRs give other contributions to the intrisic polarization 44 . We also made the assumption that we had a single domain crystal which is not the case in a real experiment. There are multiple domains, domain wall motions are induced which modify the polarization response. However, as we consider sufficient applied electric field, our hypothesis remains rather valid. Finally, the electrical losses occurring during the charging and discharging process are ignored in our modeling.

VI. CONCLUSION

In this study, we investigated the influence of crystal orientation for different ferroelectric perovskites material in order to identify the best phase transitions for optimizing the pyroelectric energy harvesting using Olsen cycles. An important additional feature of this work was to explain the negative electrocaloric peaks with the equivalence between pyroelectric energy harvested and electrocaloric effect. It is the first study in our knowledge to obtain such behavior with phenomenological approach. Moreover, a good agreement in term of order of magnitude and temperature values for the electrocaloric peaks has been obtained. The other highlight of this article is to model Olsen's cycle with Landau-Devonshire theory to predict the best thermodynamic conditions to realize realistic pyroelectric harvester devices. In all cases, the FE-PA transition maximizes pyroelectric energy harvesting. The FE-FE transitions can improve the energy density for particular orientations and electric field. On the contrary, other orientations can decrease the energy density by using FE-FE transitions. For some materials and applications, it is complicated to work in the Curie temperature region ( 100°C). While being of lower energy density compared to FE-PA transition, taking profit of FE-FE transitions could be a good alternative to increase the output energy. We demonstrated it is better to use <011> orientation and the O-T transition or the <111> orientation with the R-O and the O-T transitions for Olsen cycle. The R-O transition in a <011> oriented crystal and all the FE-FE transitions for a <001> crystal orientations will reduce the harvested energy. These results are true in the frame of a classical Olsen thermodynamic cycle. Of course, working close to the Curie temperature is still the best option for such applications. We have nevertheless shown that for this purpose, the ideal ferroelectric material will be in the <001> orientation with a small shift of the Curie temperature with electric field. This result emphasizes the point that when a transition is favorable, the ideal low temperature (T l ) is slightly before the temperature transition. Moreover, most of ferroelectric materials are solid solutions and change their temperature transitions by changing their mixing proportions. Thus, it is possible to tailor a composition to have a cycle with a low temperature (T l ) at the ambient temperature, while, made profit of the favorable phase transitions of specifics crystal orientation identified in this study. The ideal cycle would cross the transition during the heating and cross the transition back during the cooling process. Finally, the predicted energy harvested is of good magnitude and trend vs. the working temperatures. However, some discrepancies still occurs between modeling and experiments. These difference can be explained by several mechanisms. First of all, the Landau-Devonshire theory considers only a single ferroelectric domain. Secondly, there are always electrical losses when applying or releasing electric field. Another difference with a real experiment is the hysteresis with ferroelectrics. Even though the Landau-Devonshire theory can reproduce the coercive electric field, there is always hysteresis in ferroelectrics and the experimental results necessarily depend on the history of the material. Finally, in ferroelectric relaxors such as xPMN-(1x)PT and xPZN-(1x)PT, PNRs regions appears and give other contributions to the polarization. All of these contributions can be a basis for further investigations. To conclude, phenomenological approach can be useful to identify interesting thermodynamic regions and benefiting of phase transitions for real optimized energy harvesting devices.

FIG. 1 .

 1 FIG. 1. (a) Representation of a P(E) cycle with the different steps of the Olsen cycle detailed; (b) Evolution of the temperature and the electric field in function of time for two consecutive Olsen cycles in the case of T h -T l = 10K, E i = 0kV /mm and E f = 2kV /mm.

FIG. 3 .

 3 FIG. 3. Illustration of the crystal in the different orientations with the associates projection vector and basis. (a) <001> Orientation; (b) <011> orientation; (c) <111> orientation .

FIG. 4 .

 4 FIG. 4. Electrocaloric effect for BaTiO 3 in function of the temperature for different applied electric fields. (a) <001> orientation; (b) <011> orientation; (c) <111> orientation; (d) comparison between the three orientations.

FIG. 7 .

 7 FIG. 6. A plot of the harvested energy in function of the working temperature T l for PMN-30PT. (a) <001> orientation; (d) <011> orientation; (g) <111> orientation. Temperature-Electric field phase diagram versus polarization for PMN-30PT. (b) <001> orientation; (e) <011> orientation; (h) <111> orientation. A plot of the associated P(E) cycles for PMN-30PT. (c) <001> orientation; (f) <011> orientation; (i) <111> orientation.

FIG. 9 .

 9 Fig.8displays a summary of the optimum phase transitions for pyroelectric energy harvesting with respect to their crystal orientations. To compare our model with experimental results, a plot of the harvested energy depending on the temperature variation is proposed on Fig.9. In this comparison, T l is set to be constant at 373K. The experiment was performed by Khodayari et al43 on <011> oriented PZN-4.5PT with an applied electric field along the [011] direction. To determined the landau coefficients of PZN-4.5PT, we used a linear composition law with the coefficient of PZN and PT31

  -E 1 P 1 -E 2 P 2 -E 3 P 3(7) where the E i and P i are the different components of the electric field and the polarization.

	Parameter	BaTiO 3	24,29	PZN-4.5PT 30,31 PMN-30PT 25,32	Units
	T s	160	0		0					K
	T c	390	423.75	390.1				K
	α 1	5 * 10 5 * T s	1.9 * 10 5	6.22 * 10 4
						1	2 + P 2	2 + P 3	2 ) + α 11 (P 1	4 + P 2	4 + P 3	4 )
				+α 12 (P 1	2 P 2	2 + P 1 P 3	2 + P 2	2 P 3	2 ) + α 123 P 1	2 P 2	2 P 3	2
				+α 111 (P 1	6 + P 2	6 + P 3	6 ) + α 112 (P 1	2 (P 2	4 + P 3	4 )
				+P 2	2 (P 1	4 + P 3	4 ) + P 3	2 (P 1	4 + P 2	4 ))
				+α 1111 (P 1	8 + P 2	8 + P 3	8 )
				+α 1122 (P 1	4 P 2	4 + P 1	4 P 3	4 + P 2	4 P 3	4 )
				+α 1123 (P 1	4 P 2	2 P 3	2 + P 1	2 P 2	4 P 3	2 + P 1	2 P 2	2 P 3	4 )
				+α 1112 (P 1	6 (P 2	2 + P 3	2 ) + P 2	6 (P 1	2 + P 3	2 )
				+P 3 2 )) State 6 (P 1 2 + P 2 Polarization Number of Symmetry
										components configuration
				Cubic							(0, 0, 0)	1	m3m
				Tetragonal					(0, 0, P)	6	4mm
				Orthorhombic ( P √ 2	, P √ 2	, 0)	12	mm2
				Rhombohedral ( P √ 3	, P √ 3	, P √ 3	)	8	3m1
				TABLE I. Properties of the different ferroelectric phases

TABLE II .

 II List of Landau coefficients and physical properties

FIG. 2. The different possible orientations of the polarization for a ferroelectric crystal. (a) Referential of the cubic basis of the crystal; (b) Tetragonal phase with six possible orientations; (c) Orthorhombic with twelve possible polarization directions; (d) Rhombohedral and eight possible configurations.

ACKNOWLEDGMENTS

This work was performed under the framework of the ANR-FIESTA project, funded by the French Agence Nationale pour la Recherche, grant ANR-20-CE05-0026, and under the framework of the International Research Network ELyT Global.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.

AUTHOR DECLARATIONS CONFLICT OF INTEREST

The authors have no conflicts to disclose.


Solène Lambert
email: solene.lambert@sorbonne-universite.fr

Designing Surgical Telementoring Systems to Support Learning Conception de systèmes de telementoring chirurgical pour faciliter l'apprentissage

Keywords: Human-centered computing → Empirical studies in HCI; Collaborative interaction Surgery, Mentoring, Learning

Surgeons practising outside experts centers have difficulty accessing mentors to operate with them in order to update their skills. Telementoring can increase the reach of mentors by supporting mentoring at a distance but despite their potential, current systems remain rarely institutionalized. The goal of this PhD is to explore how the design of surgical telementoring systems could support learning. We present the results of a field study on mentoring needs as well as discuss implications for telementoring systems and future works.

restent rarement institutionnalisés. L'objectif de cette thèse est d'explorer comment la conception de systèmes de télémentoring chirurgical pourrait soutenir l'apprentissage. Nous présentons les résultats d'une étude de terrain sur les besoins lors du mentoring et discutons des implications pour les systèmes de télémentorat ainsi que de nos futurs travaux.

MOTS CLÉS

Chirurgie, Compagnonage, Apprentissage DOCTORAL RESEARCH OVERVIEW Surgeons acquire much of their knowledge through situated learning in what is known as mentoring: young surgeons assume the role of mentees, acquiring and perfecting skills by observing surgical interventions and progressively participating more and more under control of expert surgeonstheir mentors. Despite the benefits for learning, surgeon practicing outside experts centers, have difficulty accessing experts to update their skills [START_REF] Anvari | Telesurgery: Remote Knowledge Translation in Clinical Surgery[END_REF]. Additionally, when those mentoring sessions are implemented, the logistical constraints may limit the frequency of mentoring sessions and the scarce time of experts is wasted in travels. In this context, surgical telementoring offers promising avenues to overcome those difficulties. Surgical telementoring is defined as a relationship facilitated by telecommunication technology in which an expert surgeon (mentor) provides guidance to a less experienced learner (mentee) from a remote location [START_REF] Christopher | Project 6 Summit: SAGES telementoring initiative[END_REF]. Telementoring systems typically consist in videoconferencing systems, transmitting audio and video with added possibility to point and draw on the surgical view [START_REF] Augestad | Educational implications for surgical telementoring: a current review with recommendations for future practice, policy, and research[END_REF]. Despite their potential, telementoring is still rarely institutionalized, partly due to safety, legal, infrastructural, financial and organizational obstacles [START_REF] Anvari | Telesurgery: Remote Knowledge Translation in Clinical Surgery[END_REF][START_REF] Hung | Telementoring and Telesurgery for Minimally Invasive Procedures[END_REF]. In this PhD work, we explore the technological limitations that may hinder telementoring adoption and how to overcome them. Specifically, we inquire how the design of telementoring systems could support learning in surgery. To answer this research question, we follow a user-centered approach. That is, we start by investigating the needs in surgical mentoring. We then conceptualize new interactions mechanisms, prototype them, evaluate formally and informally with surgeons before going into these concepts with more depths. That way, we first aim to contribute empirically to the growing literature on the practice of surgical mentoring [START_REF] Feng | Communication Cost of Single-user Gesturing Tool in Laparoscopic Surgical Training[END_REF][START_REF] Feng | Improving Common Ground Development in Surgical Training through Talk and Action[END_REF][START_REF] Mentis | Learning to See the Body: Supporting Instructional Practices in Laparoscopic Surgical Procedures[END_REF][START_REF] Mentis | Crafting the Image in Surgical Telemedicine[END_REF]. Second, we will contribute conceptually through demonstrating how novel interaction mechanisms could support learning from a remote mentor. In particular, we investigate how new designs of telementoring systems could help meet the functional needs for mentoring in surgery.

UNDERSTANDING MENTORING NEEDS

During this first year of PhD, we focused on understanding mentoring needs and limitations of current telementoring systems. We did not observe situated use of systems for telementoring, as this practice has been institutionalized in very rare cases, which makes it difficult to access for research. Instead, we observe onsite mentoring as it takes place today, to gain understanding of this practice and contrast our findings with the design of telementoring tools. Existing works already provide insights on mentoring techniques such as physical demonstrations and verbal feedback [START_REF] Butler | Cognitive Apprenticeship in Orthopaedic Surgery: Updating a Classic Educational Model[END_REF][START_REF] Dunphy | Assisted performance and the Zone of Proximal Development (ZPD); A potential framework for providing surgical education[END_REF]. However, concepts such as scaffolding [START_REF] Van De Pol | Scaffolding in Teacher-Student Interaction: A Decade of Research[END_REF] widely used in educational sciences emphasize the importance to not only provide support to mentees, but to diagnose their needs, so that mentors can choose an appropriate strategy given the current context. We therefore focus on mentor's informational needs when diagnosing mentees' learning needs. We also explored mentee's perspective on mentoring, a lens that we have not seen in previous work. Our inquiry of onsite mentoring is guided by two questions. First, what are the cues that mentees exhibit and mentors perceive that inform mentor's action? Second, how do mentees benefit from the mentor's presence?

We conduct a field study where we observe 11 soft-tissue surgeries, performed through a variety of techniques (open surgery, classic minimally-invasive surgery, and robotic surgery) to grasp mentoring practices in settings that impose different mentor-mentee configurations and needs. We perform semistructured interviews with self-confrontation, with the mentor and the mentee, exploring mentors' perception of mentees, causes of communicative acts and mentors' taking over, how mentee benefited from the mentor's presence, and what mentees learned during surgery.

Through Thematic Analysis, we shed light on how mentors identify and answer the mentees' needs as well as take distance to let mentees develop autonomy. First, we identify that mentees need: to confront to difficulty, to be spared from part of the workload of the surgery, to be reassured concerning safety. The workload of the surgery refers to the numerous tasks that need to be performed during surgery as well as the necessity to take risks, to overcome difficult situations and to respect the operating room schedule Second, we observe that mentors understand these needs primarily through their observation of the surgical view, but also through inspecting the mentee's posture and the patient's body. Third, we show that the mentor's presence limits autonomy development which leads mentors to eventually physically take distance.

Implications For Telementoring

From these results, we identified the limitations of current systems, and propose avenues to overcome them. The first limitation of telementoring is the inability for mentors take action on the patient body as it prevent mentor from, understanding surgery, risk and mentees' gesture in complex situations ; from sparing mentees and helping them overcome workload, risk and blockage ; from reassuring the mentee through being available to take over "just in case". Other limitations include the absence of a viewpoint on mentee's posture to identify the cause of struggles and probable weaker implicit validation compared to onsite mentoring.

While telerobotics surgery could solve most of these issues, it would also make telementoring reserved to a few hospitals able to afford such a technology. In our future works, we therefore wish to focus on advances that improve telementoring workflow while keeping it affordable. We highlight the importance to record mentees' posture and tools outside the patient body. We show interest towards technology measuring force applied on the tissues to make texture more visible to an external observer. We emphasize that beyond creating tools to guide the surgery technically, telementoring systems need to support the mentor in increasing safety and reassuring the mentee. For instance, creating feedback to show that the mentor focuses on the surgery could enhance remote implicit validation. Lastly, tools that enable mentors to increase their control through formulating precise instruction, including at a motor level, could help overcome blockage and ensure safety in critical situations.

FUTURE WORKS

One of the core limitations of the adoption of telementoring is the lack of physicality that can prevent mentor-mentee dyads from overcoming struggles during surgery. Creating systems that compensate at least partially, this lack of physicality, may be the most impactful advancement for learning as it will create new learning opportunities through favoring telementoring adoption. We therefore shift our focus from studying learning gain to studying how mentees could overcome blockage or struggle with telementoring.

While improving mentor's instructional means is crucial to compensate for lack of physicality, making mentees' intention more explicit may also be necessary for mentors to adjust efficiently their instructions to mentees' needs. We favor avenues with a lower communication cost for the mentee as their resources is already taken by the surgical work. We identify gaze as a good avenue as it does not require effort of communication on the mentee side, while having the potential to inform mentors on the cognition of mentees. Work outside surgery identify the potential for gaze to predict intention for a driving task [START_REF] Akkil | Gaze Augmentation in Egocentric Video Improves Awareness of Intention[END_REF] as well as to guide attention, guide action, check for misunderstanding during telementoring in an electronic component assembling task [START_REF] Sung | Learners Learn More and Instructors Track Better with Real-time Gaze Sharing[END_REF]. To our knowledge, the mentee's gaze has not been used in surgery to inform mentor instructions.

The main contribution of this future work will be to understand how transmitting mentees' gaze position in real time could inform mentors, and how this could improve efficiency of instructions. We do not intend to explore automatic signal processing to interpret gaze. We plan to conduct a lab experiment on a laparoscopic simulator where participants will create mentor -mentee dyads. Standard telementoring features such as pointing and drawing will be included. The dyads will complete tasks in two conditions : with gaze, or without gaze. We hypothesize that gaze will improve task performance (time, accuracy) as mentor's instructions would be more efficient : mentors may provide additional clarification, ask less verbal confirmation for mentees' understanding, repeat less their instructions as gaze could provide feedback for mentee's understanding.


Martin Laliberté

The transformation of musical listening: the case of electroacoustic music

Introduction

The twentieth century 1 brought significant changes in the aesthetic expectations of composers as well as listeners. The musical crises of 1900-1920, together with significant scientific and technological developments, transformed the composer's purely musical mental universe into a hybrid one, incorporating visual and sonic sensitivity. Arguably, the postMTV digital era has heightened this transformation.

The present paper discusses the case of early (1942)(1943)(1944)(1945)(1946)(1947)(1948)(1949)(1950)(1951)(1952)(1953)(1954) and classical (1955)(1956)(1957)(1958)(1959)(1960)(1961)(1962)(1963)(1964)(1965)(1966)(1967)(1968)(1969)(1970) electroacoustic music of the Parisian school. This music, while apparently based on Schaeffer's theories of "acousmatic music" and "reduced listening" from 1966, is marked by a curious paradox: its thinking and sonic operational categories are clearly the result of a visual transformation. As we will see, words like "grain", "allure", "profile", "sound projector", and the frequent existence of graphic scores in musical sketches of acousmatic pieces testify to a new musical sensitivity "contaminated" by the visual domain. I suggest that Schaeffer and his colleagues were "listening with images".

To shed light on this important development, several electroacoustic concepts are discussed, and many examples of visual influence are offered. To arrive at a new understanding, the paper draws on various reissues of Schaeffer's texts as well as recent findings from his personal archives. The transformation thus presented might also elucidate the surprising ease with which some types of auteur cinema have employed electroacoustic music since the 1950s. A few cases of resurgent electroacoustic sensitivity in auteur cinema are presented to illustrate this point (Tati, Tarkovski, Lynch).

1 Before electroacoustic music and sound cinema 1.1 A time of crises, evolutions and experiments 1 The author wishes to thank Dr. Joyce Shintani for her help in putting this paper in a better English.

Electroacoustic music arrives at a defining moment in the history of Western arts. It is a time of many crises and converging factors, creating difficult problems but also opening the door to many creative solutions.

Ex. 1. Converging crises around 1900

As Ex. 1 tries to convey, music at the beginning of the twentieth century faced a series of converging crises in many areas, chief among them:

• Social and political erosion • Artistic erosion • Musical erosion ("fatigue")

The musical crisis (the overuse and fatigue of its language, models, means and aesthetics) called for solutions, as one can gather from sources such as Arnold Schoenberg's writings (1911). In tonal music, expressive chromaticism had reached a saturation point: no further note could be added to chords after the altered 13 th with all its variants. Once the symphony reached Mahlerian proportions and the opera attained Wagnerian length, the development of musical form, too, reached a limit. More pertinently to our argument, the overuse of particular orchestral instruments created a need for new instruments capable of producing music better adapter to evolving tastes and aesthetics. In addition, deterioration of the traditional "vocal" musical model paved the way for the emergence of a "percussive" model, as well as a renewed vocal model2 . Edgard Varèse rejected bowed strings precisely for such reasons: these instruments were overused and possessed a sound too traditional for his aesthetics (Ouellette 1989: 64). He preferred winds and percussions and hoped for new instruments.

A graphical or plastic transformation

An important aspect of the musical crises of the period from 1900-1910 was a profound change in the composer's thinking. The ineluctable transformation of Western music was triggered by one of the "solutions" to these crises. In order to replace the "dead" system of tonal music with a strong and efficient way of organising music, the mental landscape of the composer -and of the listener -had to become more graphic, more plastic.

A case in point is Schoenberg's evolution from traditional musical hierarchies towards a spatial sensitivity, which is clearly traceable in his writings. His demonstration advances as follows. Since all chromatic tones are to be found in every harmonic series, if one listens to the higher harmonics, the fundamental notion of dissonance is called into question, and equal temperament along with it.

"Das Bestreben, die fernerliegenden Konsonanzen (die man heute Dissonanzen nennt) als Kunstmittel anzuwenden, mußte also notwendigerweise zu manchem Irrtum, zu manchem Umweg führen. Der Weg der Geschichte, wie er sich kundgibt in dem, was an den gebräuchlichen Dissonanzen das Gebräuchliche ist, führt hier kaum zu einer richtigen Beurteilung der wirklichen Verhältnisse. Das beweisen die unvollständigen oder sonderbaren Tonreihen mancher Völker, die sich aber sicher auch auf die Natur berufen dürfen. Vielleicht sogar sind ihre Töne oft natürlicher (das heißt: genauer, richtiger, besser) als unsere; denn das temperierte System, das nur ein Notbehelf zur Bewältigung der. Materialschwierigkeiten ist, hat ja nur in wenigem Ähnlichkeit mit der Natur. Was vielleicht ein Vorteil, aber kaum ein Vorzug ist" (Schoenberg 1911a: 21) Then, since pitch and dissonance are thus now debatable, other musical dimensions can take the lead in renewing ways of composing music. Arguably, Schoenberg's famous "emancipation of dissonance" results from the diminution of the role of the note or pitch in favour of other musical dimensions (Rosen 1979: 53-56). Thus, the old musical hierarchy is transformed, ex. The musical dimensions are now "democratic"4 , equal in importance, with one or the other dimension taking the lead for a while, such as timbre in Klangfarbenmelodie. Finally, at the end of his treaty, Schoenberg renders musical dimensions in even more explicitly spatial terms, Ex.

3:

Ex. 3. Musical territories "Ich kann den Unterschied zwischen Klangfarbe und Klanghöhe, wie er gewöhnlich ausgedrückt wird, nicht so unbedingt zugeben. Ich finde, der Ton macht sich bemerkbar durch die Klangfarbe, deren eine Dimension die Klanghöhe ist. Die Klangfarbe ist also das große Gebiet, ein Bezirk davon die Klanghöhe. Die Klanghöhe ist nichts anderes als Klangfarbe, gemessen in einer Richtung" (Schoenberg, 1911a: 506)

5 .
Schoenberg's equalisation of the musical dimensions and his spatial or "territorial" approach reveal a considerable evolution of the musical imagination. Schoenberg's thinking moves its focus away from the usual musical score toward an investigation of new concepts; in this case, a many layered "map" of musical dimensions. Significantly, this evolution coincides chronologically with multidimensional mathematical approaches (the "manifolds" 6 ) in Albert Einstein's work. Moreover, Schoenberg's personal and artistic proximity to the Blaue Reiter group in the critical period 1910-20, as well as his personal experiments 7 in painting tend toward the deployment of colour and motion in space rather than the representation of traditional figures and forms, confirming the mental transformation 8 . Schoenberg was far from alone in this. A similar thought is observable in Debussy: « ...je me persuade, de plus en plus, que la musique n'est pas, par son essence, une chose qui puisse se couler dans une forme rigoureuse et traditionnelle. Elle est de couleurs et de temps rythmés.… » 9 (1907, cited in Horodyski 1998 : 223).

One could also evoke Igor Stravinsky with his very developed rhythms 10 and timbres. Varèse is also quite clear on this kind of plastic transformation. As [START_REF] Horodysky | Varèse : héritage et confluences (les masses sonores -l'espace du son -la spatialisation), Villeneuve-d'Ascq[END_REF] and Ouellette have pointed out (1989: 58), Varèse' imagination was marked by the emerging science of acoustics as well as by Schoenberg. It operates in a spatial world of at least two dimensions, where notes become points, melodies curves, chords masses or blocks in opposition, and so on, ex. 4: Ex. 4. Varèse' "mental map" ? Such representations become more frequent throughout the century, leading to many later electroacoustic graphical devices such as the UPIC 10 or the iPad 11 .

It is significant that electroacoustic music was born in this new graphical or plastic mental context. It will be a complex French artist and thinker who takes the crucial next step in this evolution.

2 Electroacoustic music 2.1 Pierre Schaeffer. A revealing biography Pierre Schaeffer is the main character of the next evolution of music. The son of a violinist and a singer, himself a telecom engineer graduate from Ecole Polytechnique (1929) and Supelec (1934), a writer of novels, plays and essays, a composer and music theoretician as well as pupil of Nadia Boulanger, Schaeffer had a lasting impact on contemporary music and sonic sensitivity. He spent his entire professional life at French Radio andTelevision (1935-1975). He is best known for his invention of musique concrète (1948), which evolved into electroacoustic music in the 1950's, and for founding the famous Paris Studio, the Groupe de Recherches Musicales (GRM).

Why radio? Schaeffer answers (1970: 29):

Mais parce que la radio, c'était très amusant ! C'était la fille un peu baroque d'une chanteuse de l'Opéra et d'un facteur, des théâtres lyriques et des P.T.T. Tout ça sortait d'une 9 Our translation : […] I am more and more convinced that music is not, in its essence, a thing that can be put into a rigorous and traditional form. It is of colour and rhythmic time […] 10 For more on this topic see Martin Laliberté (2007 Indeed, this multi-talented man chose radio as the field of research best suited for all his interests. It is the convergence of science, sound, music, literature, administration, and politics.

The far-reaching impact of microphone and radio

The invention of musique concrète was not at all accidental, rather the cumulative result of historical currents mentioned in the first part of this paper. Pierre Schaeffer came to its invention by degrees, but things accelerated during a research seminar on the artistic possibilities of the radio in Beaune in 1943. Theatre director Jacques Copeau and Schaeffer, the group leaders, along with a few radio art enthusiasts quickly came to the conclusion that the microphone could provoke a fundamental upheaval in the perception and transmission of meaning (Schaeffer 1966: 88-89):

…Le microphone, comme le microscope et comme la caméra, grossit, accuser, exagère tout ce qu'il saisit.

…Devant le microphone, il faut réprimer les habitudes du jeu scénique : la gesticulation -qui se sent -les attaques abruptes (qui produisent de l'insécurité), les brusques écarts de ton (qui nuisent à la perception distincte).

Dans tous les tons, il faut soutenir l'émission de la voix parce que ni la mimique du visage ni celle du geste ne sont là pour compléter le sens, pour rendre intelligible par le jeu ce qui n'est pas nettement audible pour la diction.

… L'interprétation devant le micro est une lecture. …L'attitude devant le micro est une attitude purement intérieure. Ce ton modéré, ce ton discret et tout intime où s'insèrent les moindres inflexions de la voix, les moindres nuances d'une sensibilité et jusqu'aux moindres tics d'une personne, si bien que l'auditeur croira, au bout d'un peu de temps, connaître le personnage qui lui parle mieux que s'il avait vu son visage, ce ton à lui seul ouvre un champ considérable à l'art du micro, un champ qui lui est propre, qui lui est exclusif. …Privée de visage, privée de l'autorité du regard, privée de mains et de corps, la voix de celui qui parle n'est pas désincarnée. Au contraire. Elle traduit l'être avec une fidélité extrême. Elle le traduit même avec indiscrétion.

… La voix qui n'a rien dans le coeur ni rien dans la tête ne peut guère toucher au micro.

… La Radio pourrait donc être une école de sincérité 14 .

Pierre Schaeffer also realised that the recording of sounds and voices and their replay at will on a "blind" apparatus (the radio with its speakers) 15 profoundly transformed the nature of listening, which became "acousmatic", referring to Pythagoras' use of a curtain during initiation of his disciples. This acousmatic music was severed from its source and could be listened to at will, permitting concentration on sonic details and properties, on its inherent "meaning", regardless of acoustic origin. picks up. …In front of the microphone, one must repress the habits of stage performance: gesturing -which is felt -abrupt attacks (that produce insecurity), brusque changes of tone (that ruin distinct perception). In all tones, one must sustain the voice because both facial mimicry and gestures lack to complete the meaning, to make intelligible by performance what is not clearly heard in the diction. …Interpretation in front of a mike is reading out loud. … Attitude in front of the mike is a purely interior attitude. The moderate tone, the discreet tone, all intimacy, where the least inflection of the voice, the least nuance of sensitivity and even a person's little twitches, so much so that the listener will believe, after a time, to know the character speaking better than if he had seen his face -this tone of its own opens a considerable field to the art of the mike, a field that is proper to it, that is its exclusive. …Deprived of the face, deprived of the authority of the gaze, deprived of hands and body, the voice that speaks is not disincarnate. On the contrary. It translates the being with extreme fidelity. It even translates it with indiscretion. …The voice with nothing in its heart nor in its head cannot be touching in a mike. … Radio, therefore, could be a school of sincerity." 15 Schaeffer (1941-42) talks about "handicapped arts": the mute cinema and the blind radio.

In 1944, Schaeffer had conducted a series of further experiments for the radio play La coquille à planètes; he wrote the script and did most of the Foley work for it, but not the music. Thus, by 1948 the stage was set for a series of experiments in composing in a new style, perhaps even a new genre 13 . Thinking modestly at first that he was "improving Foley", he discovered step by step an entirely new way of composing with sounds and noises. One can follow the daily account of these discoveries of the "most general music possible" 14 (Schaeffer 1952).

Schaeffer was a man curious about his times and he strove for a modern reconciliation of traditional poetry, literature, theater, arts as well as religious speculations, with the requirements of technocracy: science, hard facts, organisation, and big structures. To understand the impact of his work, one must accept this strange hybridisation and not separate his different sides from one another. It took a curious man to hear and see in primitive radio technologies a tool for renewing music. The implications are far-reaching, as he develops in his chef d'oeuvre, the Traité des objets musicaux (1966). After this initial step of 1948, as is well known, Schaeffer went on to found the Studio d'essais, the GRMC, the GRM and even the INA 18 , organising and leading one of contemporary music's main institutions. For those reasons, Schaeffer is rightly known as a radical acousmatic researcher.

But is the picture complete? Were Schaeffer and his team really "blind"? This article attempts to demonstrate a more nuanced view. Indeed, a detailed study of Schaeffer's writings reveals the graphic sensitivity outlined in the first part of this communication. As suggested, several of the words chosen by Schaeffer to describe sonic properties reveal a graphic or plastic/spatial sensitivity: projector, grain, fringe, node, allure, channel, mass, calibre, site, etc. are all taken from the visual domain or are often associated with vision, either explicitly or in more subtle ways. For instance, "mass" [START_REF] Chion | Guide to Sound Objects, translated by John Dack and Christine North[END_REF]) and its different "calibres" and "sites", generalise the former notion of "pitch"; but mass and its nuances are obviously conceived in 2D space pitch/intensity, or even in 3D pitch/intensity/calibre space, perhaps such as this, ex. 5:

13 Ever since there has been a lasting debate as to whether electroacoustic music is really music or an entirely new media. 14 In the sense that a generalised form of an equation (like y=a+bx) contains all the different forms of this equation. 18 The Institut National de l'Audiovisuel (National TV and Radio).

Ex. 5. Mass, sites and calibre 15

Similar discussions can be made of other key concepts, most of which exist within a multidimensional space of perceptive sound properties.

Thus, electroacoustic music possesses a significant spatial or visual part, despite its radical rejection of graphics as musical tool and its essential concentration on listening. One of Schaeffer's quandaries resided in the need to manipulate properly and, even more importantly, to think properly a new "most general" music. In addition, since traditions concerning timbre were so limited, he had to invent a new vocabulary well before the generalisation of acoustics or electronic musical instruments -at the time almost nobody had heard of dynamic envelopes or recognised the difference between vibrato or tremolo, and most could not name different shades of noise nor even accept noises as having aesthetic potential. Schaeffer's literary sensitivity, his taste for multiple art forms, and his understanding of music all came together in the invention of this new vocabulary. Sensations of all kinds -aural but also visual or tactilecame into play.

The paradoxical importance of the visual for Schaeffer becomes less surprising if one remembers his personal interest in photography16 and movies. This important citation from the In Search of a Concrete Music is quite revealing in this respect:

22nd April. Once my initial joy is past, I ponder. I've already got quite a lot of problems with my turntables, because there is only one note per turntable. With a cinematographic flash-forward, Hollywood-style, I see myself surrounded by twelve dozen turntables, each with one note. Yet, it would be, as mathematicians would say, the most general musical instrument possible.

Is it another blind alley, or am I in possession of a solution whose importance I can only guess at? (1952b, 15). Mass (midi) / intensity (dB) / calibre (%)

In this citation, famous for having the intuition of the sampler as early as 194817 , one notices the cinematic sensitivity joining the poetic and theatrical as well as the scientific -all those dimensions battling in Schaeffer's mind. Again, the terms "grain", "projector", "profile", "node", and "fringe" come to mind. Not only are these words visual in general, but they are also cinematic or photographic in particular18 . In a lesser-known proposition, Schaeffer even calls the speaker a "sonic screen", rather than a "sound projector", thereby underscoring the cinematic analogy. Indeed, the answers to these questions go back further than 1948. In the background preparation of the invention of musique concrète, Schaeffer wrote a most significant essay in 1941-42 called Essai sur la radio et le cinéma. In this fascinating early text, he drafts many aspects of his later theories well before he conceived of a new kind of music or prepared La coquille à Planètes. In the essay, Schaeffer promotes the radio drama as a carefully crafted, new, mixed media art form containing in this order: words, acting, music, and sound effects. For him, because of the technological nature of the support, this art is much more closely related to cinema than to theatre or opera. For him, both constitute "relay" or "go-between" arts (artsrelais) that share common traits. Among his sketches, a figure is particularly striking, recreated here for ease of reading, ex. 6:

Ex. 6. Relationship of a light object and sound body, left (1) to the eye and the ear, right (5), via the relays of cinema or "dynéma", (2-4) 19 .

Taken from a newly reissued text (2010), the sketch also constitutes the link between Schaeffer's literary practice and radio art. The "dynéma" he proposes remained a constant image in the Musique concrète group, eventually becoming the concept of "cinéma pour l'oreille" (cinema for the ear), frequently evoked in electroacoustic music circles20 . Very early, then, Schaeffer was contemplating a new art form akin to cinema and behaving like its visual counterpart. This analogy left many visual traces in later approaches. One can also notice that right from the start, Schaeffer used a tabular method of communication 25 , well before his famous figures in major books appeared (1952,1966). In my view, this is also a clear expression of the post-Schoenberg/Varèse graphic way of thinking described above.

Other graphic tools involved in early Schaeffer confirm this paradigm. In his notebooks, sketches, and early papers, Schaeffer makes use of different types of notation. Indeed, it may come as a surprise to some more familiar with the "militant" acousmatic attitude of the musique concrète school that Schaeffer used all kinds of notations throughout his career and urged his team to develop and use them as well, music notation having proved too limited for his needs. In his perceptive paper on the analysis of electroacoustic music, François [START_REF] Delalande | Pratiques et objectifs des transcriptions des musiques électroacoustiques[END_REF] presents several examples of notation in use at the GRM, ex. 7: The Etude violette, being piano based, can probably be transcribed more easily than other noisebased works; nonetheless, the transcription is not quite satisfactory, for it is too "reductionist", i.e., it is does not have enough detail on matters of timbre. The next example, despite staves, is more abstract due to the "criteria" related graphics, an attempt to symbolise crucial sonic phenomena, ex. 9: Ex. 10. Schaeffer's transcription of Etude aux allures (1958) 24 With its objectively precise acoustic representation and combined with notation of perceptive results, this transcription is more satisfactory, and later visual tools will often retain such a dual approach. However at the time, bathygrams and sonograms were costly and limited to short duration fragments and thus did not become usual tools. Nevertheless, no matter how incomplete or dissatisfying the results -and Schaeffer's writings and teachings are very critical on these matters -the graphic research of Schaeffer and his group remained constant. They were certainly listening to the sounds in great detail, but images were never far away.

Moreover, the images used at GRM were a bit peculiar, often complex in nature 25 . Let's look at some of Schaeffer's main figures in the final 1966 version. They can be deceptively simple. The scale of masses, for instance, seems clear at first glance, ex. 11a: Reading the texts more precisely, however, this scale can also be perceived with other symmetries: V-shaped or in espalier 27 , ex 11b: Ex. 11. b Linear, "U" or "V" Symmetries

In fact, many Schaeffer graphics are similarly multilevel. An even richer case can be found in the famous TARTYP (1966: 459), ex. 12:

Ex. 12. TARTYP 33

Again we find a tabular and symbolic approach. But this table is extremely complex, showing at first three dimensions: variations of mass, duration, and form. Looking more closely, one sees that it employs a radial symmetry with a center (9 balanced sounds), a middle level (redundant, homogeneous, wefts, pedals), and extremes (samples and accumulations). Again, this table really is a multidimensional and dynamic analysis compressed into apparent 2D. The situation becomes even more complex if one takes into account the merging of the two extremes discussed by Schaeffer. The compressed 2D becomes a kind of cylinder within a timbre-space, ex. 13:

27 Reminiscent of the fruit trees of the north-east of France, where Schaeffer was born. 33 Reproduced by permission. In spite of this graphic complexity, the communication technologies of 1966 and, most likely, Schaeffer's own thinking at the time28 excluded the topological complexities of "ndimensional" shapes. He kept to traditional 2D graphics.

Another example, the Moles Schaeffer controversy of the late 1950s, led to the abandon or at least diminished use of the acoustic inspired representation used then (1952: 207), ex. 14:

Ex. 14. Implicit 3D space 29
And yet, this 3D representation permeates all later approaches, thereby further complicating the situation by being both present and understated. The subliminal 3D space testifies to the spatial evolution of contemporary musical thinking, Schaeffer's included despite his reluctance. 30Schaeffer's thinking is also dynamic, in the temporal sense. At a time when physicists still treated the unstable portion of sound with disregard, one of Schaeffer's major achievements was to attract attention to the attack and transition of a sound's "dynamic profile", its dynamic envelope (Chion 1983: 174-178). This dynamic-temporal approach is even active in this simple looking figure, ex. 15:

Ex. 15. Four ways of listening: a cycle in time, 1 to 431 Drafted as early as 194232 , the four types of listening make a cycle: usually 1-2-3-4. Schaeffer also presents the interaction of abstract and concrete music as a cycle in time (1952: 35-36) : 1from abstract to concrete and 2-from concrete to abstract. If space permitted, it would be intriguing to present here the four parts of morphologies, the TARSOM (Schaeffer 1966: 584587). This elaborate figure shows complex and intricate multidimensional and temporal organisations, despite an apparent 7*9 grid.

In its place, let's pay attention to an animation film produced by François Delalande and Jacques Vidal for the GRM (c. 1970) 33 . Here, one can understand just how important images were for the Paris group and how the subsequent Acousmographe was the crowning achievement of those attempts, as Delalande demonstrates (2009). In spite of technical limitations in this animation film, different shapes are used to represent sounds and their properties according to a more or less Schaefferian analysis34 . The representation derives from the musical score, being mass in function of time, and includes a representation of the dynamic envelopes and some references to timbre, although it does not yet scroll 35 . Instead, a pointer is used in synchronisation with the music.

To conclude this part of the article, I stress that the surprising presence of visual aids for listening in GRM practices does not appear to be a contradiction of the group's founding principles. The use of visual aids does not diminish the true originality of this musical school: listening to sounds of all kinds with curiosity and concentration, reaching for ways to put them together to create satisfactory aural experiences. However, such originality does not necessarily preclude a visual approach. I have shown many cases where the eye was involved as well as the ear to forge a characteristic manner of listening to and composing music. In the words of one of the GRM's main figures, François Bayle, "Yes, of course, we used some visual tools, but always under the control of the ear. It would be a mistake to think that because of our concentration on listening we were blind. On the contrary".36 Like Schaeffer, Bayle's approach often presents visual aspects, despite his concentration on acousmatic music.

The persistence of the visual in electroacoustic practice can shed light on a complementary discussion related to this conference's theme.

3 Some cases of electroacoustic resurgences in auteur cinema A somewhat surprising fact of art history is the ease with which cinema integrated electroacoustic sensitivity, considering that film is a rather conservative medium concerning music. Could this be related to the half-hidden visual side of electroacoustic music? Let us discuss a few pertinent cases.

Electroacoustic thinking is a musician's approach, but sound engineers are usually musicians as well. Gradually, electroacoustic sensitivity reached the cinema world and exerted an impact, almost automatically. This impact can be explained in part by the necessity for directors and moviemakers to find new ways to use sound in the reconstruction of reality that is film. For certain avant-garde projects, traditional music is not always appropriate, diverting attention from other aspects of the film or giving a romantic or overly "produced" effect. Sound, ambient noise and soundscapes are used instead.

These two explanations converge towards a creative use of sound, where two major tendencies are observable:

1-a direct link from film to the electroacoustic community. Quite a few soundtracks from 1950 onward were composed by trained contemporary composers (Morricone, Fano, Constant, Artemiev…) or were commissioned by directors with a high degree of musical sensitivity (Disney, Kubrick, Lynch, Godard, Visconti, Coppola, Lucas).

2-

a more frequent indirect link. In a technical, "mediological" (Tiffon 2005), and practical way, soundstages and cinema studios are true electroacoustic studios, often benefiting from ample budgets and the best technologies. They "exude" electroacoustic music, even without even realising it consciously37 . As Marshall McLuhan has clearly shown (1964), "the medium is the message": a tool contains its own immanent properties that lead the user towards a certain way of doing things and the listener of perceiving them. To paraphrase Molière (1670), several sound designers for film are doing electroacoustic music "in spite of themselves".

A problematic microphone

For better or worse, the camera and the microphone joined forces in the late 1920s. As the 1952 movie by Gene Kelly and Stanley Donen, Singin' in the Rain, lampoons, this marriage was not easy at first. Great creativity, artistic and technical, was necessary to overcome such problems as unwanted "microgenic" sounds and noises, conflicting needs of recording (a quiet stage and proximity of the microphone to the source) and of filming (excluding the presence of the microphone from the frame and including a noisy camera on stage), and of an adapted acting different from traditional "extroverted" theatre acting 38 . Once more, "… radio could therefore be a school of sincerity". The opposition between stage acting and the Actors' Studio method also comes to mind. After "moving" pictures, from 1930 onward a new generation invented "talking", "sounding", or even "singing" cinema; and it achieved spectacular success in the late 1940s, as the Kelly and Donen film celebrates, including superb broadcast technical quality. Hifi microphones and speakers have not improved all that much since the 1950s.

Auteur cinema and music

On the fringes of the movie industry, more demanding artists in auteur cinema also adopted the apparatus of moving and sounding images. In a few cases, sonic aspects take a singular place, recalling the primitive biological function of hearing: to inform the individual about what cannot be seen. Auteur cinema also rediscovered the function that music has filled since Gregorian chant: to express what cannot be told. Finally, sound in auteur cinema took over the function of the old Greek chorus: to comment on and react to the action. This role had been fulfilled by music, notably with Wagner's leitmotiv, and certainly cinema 39 can be described as a new kind of Gesamtkunstwerk. It must be pointed out that film composers tend to be Wagnerian, whereas sound designers -the sons and daughters of Roy Disney or Spike Jones -often have a more modern, i.e., more creative or even fully electroacoustic approach. We illustrate this with a few examples. Tati (1907Tati ( -1982)): slapstick concrète Jacques Tati, an important director for our discussion, created an original type of cinema, in which humour and slapstick thinly disguise an anguished sensitivity towards modernisation, seen as dehumanising. In Tati's films, things dominate man, and true communication has disappeared. This is especially the case in Mon Oncle (1958) 40 . In their ultra modern villa 41 , the Arpel family no longer communicates, it speaks solely in empty advertising slogans: "Tout communique", "Comme c'est original". They live in a mechanical and obsessive way, becoming the servants of their house and its furniture -of the dolphin fountain, for instance. The "uncle", who often visits his brother-in-law Mr. Arpel, is a clumsy but charming man, never quite fitting in despite good intensions, who introduces refreshing chaos into the household 42 . Dialogue becomes almost impossible -one is reminded of Magritte. Sounds and noises, of people, things, and places, often take its place. Tati uses a close microphone and unnatural amplification of sounds to bring sounds forward in the mix, literally constructing a study in expanded sounds similar to the Schaefferian approach. The amplified dress noises of Mrs. Arpel, the detailed and contrasting sounds of steps over various materials or the menacing machine sounds, either in the kitchen or in Mr. Arpel's factory, are quite evident.

Jacques

In Traffic (1971), chaos and noise dominate the French-style derisive road movie. It, too, is at times a very attentive electroacoustic study. An interesting example is right after the tumultuous car crash 43 . A red Volkswagen Beetle turns into a wild animal, "quacking" like a duck and making savage "grinding" noises, while a wheel "runs away" for and finally falls over with exaggerated metallic sounds. This is very close to early musique concrète aesthetics, where sounds metamorphose into surrealistic otherness, like the "whale" or "singing" squeaking doors of Pierre Henry's Variations pour une porte et un soupir (1963). Those studies in sounds could also be compared to the Etudes de bruits (1948) of Schaeffer, especially the metallic sound of the falling wheel near the beginning of Etude pathétique 44 . Both creators share a distrust of modernity, as can be gathered form Schaeffer (1970) and from the movies of Tati. Incidentally, both men are from the same "disillusioned" generation, who were born before the Great War and were young adults on the eve of the Second World War.

Andrei Tarkovski: studies in maters or elements

Another case in point is Andrei Tarkovski, director of only a few but highly regarded films in which sound, music, and noise often replace missing or impossible dialogue. Tarkovski's personal idiom is developed not in satire or comedy like Tati, rather in "visionary", "poetic", even "mystic" films.

A striking feature of films such as Stalker (1979) 45 and Solaris (1979) is the director's taste for the elements, in the old Greek sense: water, air, fire, lava, stone, wood, grass, and metal find strong places, both in images and in sounds 52 . In Stalker, the whole initiatory journey into the "zone", where natural life has taken over the world from man, is a detailed study of textures, colours, and sounds, akin to mature electroacoustic music. Those soundtracks approach the work of composers like François Bayle (Tremblement de terre très doux, 1978) or Bernard Parmegiani (De natura sonorum, 1975).

Solaris also puts forward technological sounds such as cars on a highway 46 , the sounds of the space station, etc. This creates a subtle comment on the state of mind of the cosmonaut and his apprehensions before his mission. Again, man seems small and menaced against such a sonic (and visual) ambience. Like the two compositions mentioned above, the soundtrack composed by Eduard Artemiev makes use of both recorded and synthesized sounds, thus being fully electroacoustic or even mixed-music rather than musique concrète.

It should also be noted that this film is a late but fervent inheritor of the space race, seen from the USSR side, beginning with the science fiction literature of Stanislas Lem and his cohort, possibly the result of being "red children". This might be compared with successful US movies such as The Right Stuff or Apollo 13. The particular fervour of Tarkovski is evident in the "apparition and levitation" 47 scene at the end of the movie, where the main character and the "spirit" of his deceased wife float in the air, accompanied by an organ piece of Bach. To modernise the sound and give it distance, the composer doubles the organ with vibraphone, lending a contemporary or jazzy tone 48 . Thus, the cosmonaut is presented as a kind of "secular saint", surrounded in the space station by examples of European fine art at its best. This also represents a kind of redemption of the main character (another signature of saints), confessed and blessed by the planet Solaris.

David Lynch and post-industrial individual anguish

Yet another example of electroacoustic sensitivity can be seen in David Lynch's film Eraserhead (1977). This dark and humorous movie is an interesting case of post-space age "crash" -in drug parlance, the "coming down" of the 1970s after the "high" of the 1960s.

The tribulations of Henry with his fiancée-turned-too-quickly-wife and their baby in sordid parts of Philadelphia as he suffers from visions, hallucinations or even the real madness of the period, are constructed with few or empty words and foreground sounds, noises, and music. For instance, in the mad first meal 49 with his soon-to-be family-in-law, we hear organic bubbling and disgusting noises, revealing the embarrassment of Henry and anticipating the problematic result of his relationship: a baby, with its share of unavoidably physical and dirty aspects. The movie is often visually "drenched" in liquids and dubious looking matter, accompanied by disturbing sounds. The "man in the planet" -either a deus ex machina or a demon plotting and torturing Henry -is accompanied by amplified sounds and menacing machine or train-like noises 57 (perhaps those from Philadelphia's closing factories at that time of economic crisis). On another level, the singing "lady in the radiator" 50 is a complex chimera: a woman resembling Marilyn Monroe who has cheeks that look like testicles and who sings in a man's falsetto becomes a good fairy or angel, apparently relieving Henry from his mad life.

The soundtrack is fascinating and well constructed, if one accepts noises as legitimate artistic sounds. Broken down Philadelphia recalls the basic sounds recorded there by Varèse for his 1950-54 Deserts, while the embarrassed silences of the family meal, the expressionist silent scream of Mary's mother, and the organic sounds recall early electroacoustic pieces like Luciano Berio's disturbing Visage (1961). Finally, the dark humour and deconstruction characterising the movie in all of its aspects are related to contemporary post-modern thinking. Berio again comes to mind, especially Sinfonia (1968), a landmark in deconstructive approaches to music.

To conclude: listening with images After summarising the growing importance of visual or spatial imagination on modern and contemporary music as a solution to the post-Wagnerian tonal music crisis, this paper studied the case of early electroacoustic music. Schaeffer and his school were presented as inheritors of the pioneer musical-spatial-visual shift of paradigm by composers such as Schoenberg, Debussy, Stravinsky and Varèse. In that perspective, sounds of all kinds are deployed and interact in a mental and perceptive multidimensional space of complementary musical properties.

Recent reissues, better translations of founding texts, direct discussions with the actors, and archive findings reveal a surprising and complex use of visual aids in radical acousmatic circles in the 1950s and 1960s, despite severe criticism and distrust. Schaeffer and his teams 49 http://www.youtube.com/watch?v=SqV41XH_dLI. Retrieved in August 2013. 57 This appears close to Schaeffer Etudes aux chemins de Fer (1948). 50 http://www.youtube.com/watch?v=59ZHZxsqs5M. Retrieved in August 2013.

listened with concentration and subtlety to sound, but they did so with visual assistance -"always under the control of the ear", confirms Bayle. The key concepts, many of which stem from vision or touch rather than from hearing alone, and the tables, graphs and other visual aids were constructed and improved over the years leading to Schaeffer's fundamental texts of 1966-67 and then, after many more years of composition and research, to Acousmonium, GRM's music analysis software.

The simultaneous presence of the visual dimension in electroacoustic practice may explain the success of electroacoustic music in cinema, both in practice and in theory [START_REF] Chion | Guide to Sound Objects, translated by John Dack and Christine North[END_REF]. Many auteur films from the 1960s to the 1980s -Tati, Tarkovski, Lynch -demonstrate clear electroacoustic sensitivity, as if the electroacoustic approach was naturally cinematographic.

In all of these ways, and with these ramifications, the Paris school was listening with images.

  tonal music and loss of m eaning of its hierarchies -Aging and wear of musical romanticism -Aging and wear of the orchestra -Emergence of timbre and rhythm -Decadence of the vocal model and emergence of the percussive model -Important diversification of virtuosity Artistic c rises: -Distrust towards official arts l -Lack of confidence in the traditional values -Counter -example of non -western arts Western socio -political crises: -Distrust towards official institutions and their policies -Loss of confidence in the traditional values -Counter -examples non -western cultures

  Ex. 7. Schaeffer's sketch for a symphonie de bruits (1948) 21 This sketch of an early version of the Etudes concrètes, mixing musical notation, drawings, rhythms, and measures, is closely related to the well-known sketch of the Etude aux chemins de fer (1948). Both reveal a dominating spatial conception inherited from musical notation that is potentially multidimensional. For confirmation, let's look at other examples by different members of his teams. This example from 1952 by Monique Rollin is still close to musical notation, ex. 8: Ex. 8. Monique Rollin's transcription (1952) of Etude violette 22

24

  Reproduced by permission.25 Possibly an inheritance of the esoteric practices that seduced Schaeffer for a time (Schaeffer 1970).26 Given here in John Dack and Christine North's translation of Michel Chion's Guide de l'objet sonore[START_REF] Chion | Guide to Sound Objects, translated by John Dack and Christine North[END_REF]), in EARS, 2009. Retrieved in March 2013.

  . A cylinder in multidimensional timbre-space

  ). 10 http://en.wikipedia.org/wiki/UPIC. Retrieved in August 2013. 11 http://www.ipadmusicapps.ca. Retrieved in August 2013. 'un micro à charbon type 1929, et tout ça, bien entendu, étant contrôlé par un Père Fouettard délégué par la rue de Rivoli pour surveiller le tout. Ça me fascinait bien plus que de me retrouver dans le laboratoire d'une entreprise privée. C'est poétique, les ondes, et puis le service public, ce n'est pas rien pour qui a l'inspiration civique 12 .

	boîte à lampes et d
	Pitch
	Time

For many developments of this proposal, see, MartinLaliberté (2014) and (2008).

"Efforts to make use of the more remote consonances (today called 'dissonances') as artistic means thus led necessarily to many an error, to many a detour. The way of history, as we can see it in that which has a cruelly been selected by practice from the practicable dissonances, hardly leads here to a correct judgment of the real relations. That assertion is proved by the incomplete or unusual scales of many other peoples, who have, nevertheless, as much right as we to explain them by appeal to nature. Perhaps their tones are often even more natural than ours (that is, more exact, more correct, better); for the tempered system, which is only an expedient for overcoming the difficulties of the material, has indeed only a limited similarity to nature. That is perhaps an advantage, but hardly a mark of superiority (1911b: 21).

The political parallel is relevant at the time of the downfall of the Austrian Empire(Schoenberg 1951).

« Je ne puis admettre sans réserve la différence que l'on a coutume d'établir entre couleur sonore (timbre) et hauteur sonore. C'est en effet par sa couleur sonore -dont une dimension est la hauteur -que le son se signale. La couleur du son est donc le grand territoire dont une région est constituée par la hauteur du son, Cette dernière n'est rien d'autre que la couleur du son mesurée dans une direction.»(Schoenberg 1911c : 516) Interestingly, the French translation given here is closer to the German original in its use of a territorial metaphor, whereas the usual English translation(Schoenberg 1911b : 421) uses a much more traditional figure of speech, that of direction, masking the important spatial aspect. This detail might contribute to a useful debate on the translations ofSchoenberg, someday.

Associated with Gauss and Riemann. See "manifold" in en.wikipedia.org. Retrieved in March 2013. http://en.wikipedia.org/wiki/Riemannian_manifold.

The website of the Arnold-Schoenberg Center is rich in details on this and many other topics. Retrieved in March 2013. http://www.schoenberg.at/index.php?option=com_joomgallery&Itemid=339&lang=en.

Before his return to a more traditional predominance of the pitch in the twelve-tone system in the 1920's.

Our translation from French: "But because radio was very amusing! It was the baroque daughter of an opera singer and of a postman, of the lyric theatre and the post-office. And it all came out of a lamp-box and a coal-microphone of type 1929. And all that, of course, controlled by a bogeyman from the rue de Rivoli to watch over everything. It fascinated me much more than being in the laboratory of a private enterprise. It's poetic, the waves, and public service is something for those who have civic inspiration". Note that the Ministry of Finance was then located on Rue de Rivoli.

For ease of representation, the pitch center of the masses is represented by its equivalent and the usual MIDI number, despite the anachronism of this practice. Schaeffer was using a traditional scheme of note names and numbered octaves which gives a similar linear pitch scale.

There were known photographers in his family and there remains an interesting collection of art photographs in his personal archives conserved at IMEC in the city of Caen.

Harold Chamberlin (USA) had quite the same idea the very same year, this leading to his tape based instrument and the better known Mellotron (UK).

"Grain", "node" and "fringe" are also tactile. Frange (fringe) has been translated as "white noise" elsewhere, which is clearer but obscures the visual analogy to the fringe of a rug. Schaeffer often uses the term frange for broadband noise, preferring the concrete image of a disorderly fringe around a shawl or rug to the "scientific" term that misses in his view the qualitative or perceptive point.

Mise en rapport de l'objet lumineux et du corps sonore à gauche (1) avec l'oeil et l'oreille à droite (5) par les relais du cinéma et du dynéma (2-4).

Notice, for instance, the name of the well-known CD collection, edited byMetamkine. 25 This can also be an inheritance of his engineering training at l'Ecole Polytechnique.

One often finds in him a dual tendency towards extreme modernity and towards a nostalgia of simpler times.

Reproduced by permission.

I would argue that he was, along with Schoenberg, a "reluctant Messiah", to borrow the term from Richard[START_REF] Bach | Illusions : the Adventures of a Reluctant Messiah[END_REF], or a "sleepwalker" according to Arthur[START_REF] Koestler | The Sleepwalkers: A History of Man's Changing Vision of the Universe[END_REF] -never quite sure if he really wanted to go along with his avantgarde invention. I will shortly publish on this subject (2014).

Reproduced by permission

See Schaeffer 1942, p. 53 and 61.

An excerpt can be found at : http://fresques.ina.fr/artsonores/fiche-media/InaGrm00206/partition-animee-de-l-etudeauxobjets.html. Retrieved in August 2013.

 34 Schaeffer himself was not a fundamentalist and kept a distanced relationship to analysis; he was, instead, rather pragmatic, seeking usefulness rather than perfection (Schaeffer 1967).

François Bayle, personal oral communication, January 2013. Our translation.

I have proposed (2001 and 2003b) that pop-music studios had the same evolution towards a electroacoustic sensitivity, explicit or unconscious.

Ex. 9. Mireille Chamass' transcription of seven sound objects (1959) 23

Third, let's look at an example of double notation, contemporary to example 9, including both the bathygrams and musical transcriptions, ex. 10: