Antonio Sorrentino
email: antonio.sorrentino@levelav.nl

Alessia Frescura
email: alessia.frescura@liverpool.ac.uk

Carmen Rosas-Pérez
email: carmen.rosas@chalmers.se

Xiaoxue Shen
email: xiaoxue.shen@liverpool.ac.uk

PERCEPTUAL BASED SOLUTION DESIGN FOR THE ANNOYANCE PRODUCED BY A WASHING MACHINE OVER A LIGHTWEIGHT FLOOR: A CASE STUDY IN THE NETHERLANDS

Keywords: Lightweight buildings, Vibrations, Low frequencies, Annoyance

Lightweight buildings are increasingly popular in Europe due to their lower carbon footprint, speed of construction and flexibility in the design of spaces. However, the inherent lightness of its structure affects sound and vibration insulation properties, especially at low frequencies. Washing machines represent a difficult equipment to insulate. In this case study, part of the ITN project 'Acoutect', the behaviour of a washing machine situated over a real lightweight wooden joists floor has been analysed. Measurements with accelerometers and binaural recordings have been performed in a two-storey masonry house in the Netherlands, in which the first floor is used as laundry while the room underneath is used as bedroom. The core idea of the approach is to split the characterization of the problem in two binaries, merging technical solution and user perception. The results from a subjective evaluation serve as basis for the design of the optimal solution, targeting the specific frequency range of the different washing cycles causing major annoyance on the users.

INTRODUCTION

In contemporary lightweight construction, washing machines represent difficult equipment to insulate, due to their complex dynamic behaviors and the variety of phases during their working cycle. A unique solution is not yet available to tackle the washing machine noise problem in which the elements to consider are multiples: machinery (source), structure (receiver), coupling condition (connection) and annoyance perceived by users. The core idea of this paper is to split the characterization of the problem into two binaries, merging technical solutions and user perception. The investigation took place is a two-storey masonry house in The Netherlands where dwellers were looking for a solution to tackle the annoyance caused by their washing machine which is installed on a wooden lightweight slab. As shown in Figure 1, the case study is a detached house in which the first floor (source room) is used as laundry while the room underneath (receiving room) is used as bedroom.

METHODOLOGY

In this project, the subjective evaluation is investigated in terms of annoyance and serves as basis for the design of a technical solution. A series of in-situ recordings and measurements were carried out (Figure 2). Filtered signals were used in the listening test with the aim of identify which would be the optimal condition for the users (e.g. critical frequency range, critical part of the washing cycle, etc.). A wooden floor and a washing machine can have infinite unique coupling conditions in an in-situ measurement. A full description of the system physics is bounded to the evaluation of the source, the receiver, and the contact conditions properties. Sound in both the source room and the receiving room were measured when the washing machine has two different loads: 1) 4-7 kg dry/wet towels, resembling a common realistic load for the machine; and 2) 300g magnets, a load which allow good repeatability of measurements. The recordings were then used in the listening test. For its setup, some clips from the binaural recordings of the spinning cycle with the towels load were extracted. The signals were digitally filtered to simulate different floor configurations when: 1) adding an additional carpet finish; 2) adding a floating floor; 3) adding a floating floor and a suspended ceiling. Different types of quantities were measured as shown in Figure 3. Those quantities were used also for an in-situ source characterization purpose. The washing machine, a force hammer and a tapping machine were used as sources, the last one of which was used as a known reference source for a comparison with the washing machine. Operational velocities were recorded at the four contacts and on different structural elements to monitor the dominant vibrational paths. Sound pressure levels in the source and receiving room were recorded as well. The dynamics of the washing machine-timber floor system was obtained experimentally with a force hammer. To validate the estimated source properties, labmeasurements with a twin washing machine was also carried out.

RESULTS

No significant difference was found between the two loading conditions in terms of velocity level of the floor and sound pressure level in the receiving room. The spinning cycle phase was identified as the loudest part. A frequency spectrum analysis highlighted a peak in the low frequency range, 120dB at 26.6Hz, which is due to the rotational speed of 1600rpm during the spinning cycle. The results of the listening test (Figure 5) show decreasing annoyance when installing a carpet, a floating floor or a floating floor and suspended ceiling solution. Similar trend is followed by the perceived loudness while when asking how thumbing the sound was the ratings made almost no difference between the three solutions investigated

CONCLUSION

The measurement outcomes highlight the sound pressure level is characterized by a peak of 120 dB at 26.6Hz. This suggests the importance of reducing the sound pressure level in the low frequency range. To increase the acoustic comfort in the receiving room, an insulating solution should be tuned in order to cut out the fundamental tone and its harmonics. The listening test results suggests that the preferred solution, in terms of annoyance, would be to install a floating floor system. The slight further preference that would be achieved with an additional suspended ceiling installation seems not significative to justify the loss of volume in the receiving room.

Figure 1 .

 1 Figure 1. View of the house (left), laundry room (upper right), bedroom (lower right).

Figure 2 .

 2 Figure 2. Recordings in the receiving and source room.

Figure 3 .

 3 Figure 3. Measurements of operational velocities (upper left), coupled mobilities (upper right), and transmission function (lower left: force hammer, lower right: tapping machine).

Figure 4 .

 4 Figure 4. Velocity of the floor.

Figure 5 .

 5 Figure 5. Listening test results.

10.48465/fa.2020.0266

e-Forum Acusticum, December 7-11, 2020

ACKNOWLEDGEMENTS

This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No.721536.


Marie-Sophie Meuleman

Veronique Fremeaux-Bacchi

Lubka T Roumenina
email: lubka.roumenina@sorbonne-universite.fr

Sophie Chauvet
email: sophie.chauvet@aphp.fr

Ex-vivo complement activation on endothelial cells: research and translational value

Keywords: Complement, Endothelial Cells, Diagnostics, Kidney injury

The spectrum of human diseases with complement contribution is ever increasing. Tools to study the complement contribution and the potential interest of novel complement inhibitors in clinical practice are lacking. Here we discuss a functional ex-vivo assay to monitor complement activation on endothelial cells, which can answer to this need.

Complement in diseases and currently available tests for its exploration.

Complement is important part of innate immunity (Box 1), but can also, when overactivated, cause tissue damage. While complement overactivation is the central mechanism of cell and tissue injury in complement mediated diseases as atypical Hemolytic and Uremic Syndrome (aHUS), C3 Glomerulopathy and Paroxysmal Nocturnal Hemoglobinuria, contribution of complement has been reported in pathophysiological processes of a large variety of conditions (i.e Age-related Macular Disease, Antibody Mediated rejection, Cryoglobulinemic Vasculitis, IgA vasculitis, Systemic Lupus Erythematous, Anti-Phospholipid Syndrome, ANCAassociated vasculitis, Rheumatoid Arthritis, HELLP syndrome, pre-eclampsia, Sickle Cell Disease (SCD)) in which vascular endothelium is one of the first targets of the overactive complement. Complement-blocking therapeutics are now considered in these diseases.

Therefore, there is an unmet need of tools, allowing disease-relevant evaluation of which patient could benefit from such therapeutic approach.

Exploration and demonstration of complement overactivation and its implication in human disease is a cornerstone of the diagnosis and management. Most of the tests, currently available, consist of 1) the quantification of complement activation fragments released in blood or 2) deposited on tissue or relay on 3) lysis of animal erythrocytes or 4) C5b-9 deposition in an ELISA plate. More specific functional tests, including hemolytic assays, exploring specific steps of the AP regulation (FH functional defect or C3 convertase stabilization) still lack approved international standards, are used by small number of specialized laboratories [2]. Only few assays, such as the CH50 hemolytic test, are used to follow complement-targeting treatment but this test is not well correlated with disease activity and relapses risk [START_REF] Galbusera | An Ex Vivo Test of Complement Activation on Endothelium for Individualized Eculizumab Therapy in Hemolytic Uremic Syndrome[END_REF]. Despite the increased understanding of the contribution of complement in diseases, validated assays, judging whether complement inhibition will be therapeutically relevant are missing. Therefore, there is a real need to develop tools to demonstrate the implication of complement in diseases in order to adjust treatment regiments and improve patient's management.

Endothelial cells assay: could it be used to improve patient management?

In order to explore the complex interplay between complement and human cells, several authors proposed to quantify complement fragments deposition on endothelial cells (EC) incubated with serum or plasma from patients with different pathological conditions (Figure 1). This ex vivo assay is the closest to the physiological context available and holds great promise. Nevertheless, there are several unanswered questions and obstacles to overcome.

-Which EC to be used? Main EC type used for this assay are HMEC-1 [START_REF] Galbusera | An Ex Vivo Test of Complement Activation on Endothelium for Individualized Eculizumab Therapy in Hemolytic Uremic Syndrome[END_REF][START_REF] Noris | Dynamics of complement activation in aHUS and how to monitor eculizumab therapy[END_REF][START_REF] Palomo | Complement Activation and Thrombotic Microangiopathies[END_REF][START_REF] Timmermans | C5b9 Formation on Endothelial Cells Reflects Complement Defects among Patients with Renal Thrombotic Microangiopathy and Severe Hypertension[END_REF], immortalized Human dermal Microvascular Endothelial Cells (HMEC); HUVEC [START_REF] Roumenina | A prevalent C3 mutation in aHUS patients causes a direct C3 convertase gain of function[END_REF][START_REF] Roumenina | Hyperfunctional C3 convertase leads to complement deposition on endothelial cells and contributes to atypical hemolytic uremic syndrome[END_REF][START_REF] Frimat | Complement activation by heme as a secondary hit for atypical hemolytic uremic syndrome[END_REF][START_REF] Roumenina | Complement activation in sickle cell disease: Dependence on cell density, hemolysis and modulation by hydroxyurea therapy[END_REF], primary macrovascular EC from human umbilical vein, CI-GEnC [START_REF] Roumenina | A prevalent C3 mutation in aHUS patients causes a direct C3 convertase gain of function[END_REF][START_REF] Roumenina | Hyperfunctional C3 convertase leads to complement deposition on endothelial cells and contributes to atypical hemolytic uremic syndrome[END_REF][START_REF] Frimat | Complement activation by heme as a secondary hit for atypical hemolytic uremic syndrome[END_REF], conditionally immortalized glomerular EC; phosphatidylinositol-specific phospholipase C-treated EA.hy926 cells EC line and PIGA-mutant TF-1 (non-endothelial) [START_REF] Gavriilaki | Modified Ham test for atypical hemolytic uremic syndrome[END_REF]. Obtained results with these cells are generally similar. Nevertheless, these cells differ in their expression of complement regulators and susceptibility to stress stimuli, such as heme [START_REF] May | Heme Drives Susceptibility of Glomerular Endothelium to Complement Overactivation Due to Inefficient Upregulation of Heme Oxygenase-1[END_REF] with higher C3 deposit, weaker FH binding and Thrombomodulin up-regulation in CI-GEnC compared to HMEC and HUVEC. Optimally, the assay should be performed with a cell line that is well characterized, widely available and easy to use, as HMEC-1, to avoid the inter-cellular variability, which may be expected with primary cells.

-Is EC pre-activation needed? Resting or pre-activated (by cytokines, ADP or heme) EC can be used, providing complementary information. The use of resting EC seems to generate more specific results, with a correlation of increase deposits on quiescent HEMC-1 with relapse risk during Eculizumab dosage tapering or discontinuation [START_REF] Galbusera | An Ex Vivo Test of Complement Activation on Endothelium for Individualized Eculizumab Therapy in Hemolytic Uremic Syndrome[END_REF]. On the opposite, pre-activated EC provide more sensitive results with positivity while incubated with serum from asymptomatic carriers of mutations in AP regulatory proteins or C3 [START_REF] Noris | Dynamics of complement activation in aHUS and how to monitor eculizumab therapy[END_REF][START_REF] Roumenina | A prevalent C3 mutation in aHUS patients causes a direct C3 convertase gain of function[END_REF].

-Serum or activated plasma? While most of the studies used patients' serum as complement source [START_REF] Galbusera | An Ex Vivo Test of Complement Activation on Endothelium for Individualized Eculizumab Therapy in Hemolytic Uremic Syndrome[END_REF][START_REF] Noris | Dynamics of complement activation in aHUS and how to monitor eculizumab therapy[END_REF][START_REF] Timmermans | C5b9 Formation on Endothelial Cells Reflects Complement Defects among Patients with Renal Thrombotic Microangiopathy and Severe Hypertension[END_REF][START_REF] Roumenina | A prevalent C3 mutation in aHUS patients causes a direct C3 convertase gain of function[END_REF][START_REF] Roumenina | Hyperfunctional C3 convertase leads to complement deposition on endothelial cells and contributes to atypical hemolytic uremic syndrome[END_REF][START_REF] Frimat | Complement activation by heme as a secondary hit for atypical hemolytic uremic syndrome[END_REF][START_REF] Roumenina | Complement activation in sickle cell disease: Dependence on cell density, hemolysis and modulation by hydroxyurea therapy[END_REF], Palomo et al proposed to use patient citrated plasma mixed with control serum pool (1:1). This allows a lower coefficient of variation of data, namely 9 to 18% [START_REF] Palomo | Complement Activation and Thrombotic Microangiopathies[END_REF] as compared to 30 to 52 %, with patient sera. The rational for the citrate use might be an interaction between coagulation and complement cascade, as illustrated by collocated fibrin and C5b-9 deposits. Patient-derived autoantibodies could be tested when added to normal human sera (NHS), as for anti-C3b in lupus nephritis [13]or recombinant patient mutationscarrying proteins, when added in depleted serum, as done for Factor B in aHUS [START_REF] Roumenina | Hyperfunctional C3 convertase leads to complement deposition on endothelial cells and contributes to atypical hemolytic uremic syndrome[END_REF].

-Which controls are needed? An international standard and validated positive and negative controls are needed for this test. The most frequently used negative control is a set of NHS [START_REF] Galbusera | An Ex Vivo Test of Complement Activation on Endothelium for Individualized Eculizumab Therapy in Hemolytic Uremic Syndrome[END_REF][START_REF] Noris | Dynamics of complement activation in aHUS and how to monitor eculizumab therapy[END_REF][START_REF] Roumenina | A prevalent C3 mutation in aHUS patients causes a direct C3 convertase gain of function[END_REF][START_REF] Roumenina | Hyperfunctional C3 convertase leads to complement deposition on endothelial cells and contributes to atypical hemolytic uremic syndrome[END_REF][START_REF] Frimat | Complement activation by heme as a secondary hit for atypical hemolytic uremic syndrome[END_REF][START_REF] Roumenina | Complement activation in sickle cell disease: Dependence on cell density, hemolysis and modulation by hydroxyurea therapy[END_REF] or pooled NHS, to avoid the inter-individual variability in deposits induced by normal sera [START_REF] Galbusera | An Ex Vivo Test of Complement Activation on Endothelium for Individualized Eculizumab Therapy in Hemolytic Uremic Syndrome[END_REF][START_REF] Palomo | Complement Activation and Thrombotic Microangiopathies[END_REF][START_REF] Timmermans | C5b9 Formation on Endothelial Cells Reflects Complement Defects among Patients with Renal Thrombotic Microangiopathy and Severe Hypertension[END_REF]. Often positive control is lacking [START_REF] Galbusera | An Ex Vivo Test of Complement Activation on Endothelium for Individualized Eculizumab Therapy in Hemolytic Uremic Syndrome[END_REF][START_REF] Noris | Dynamics of complement activation in aHUS and how to monitor eculizumab therapy[END_REF][START_REF] Palomo | Complement Activation and Thrombotic Microangiopathies[END_REF][START_REF] Roumenina | Hyperfunctional C3 convertase leads to complement deposition on endothelial cells and contributes to atypical hemolytic uremic syndrome[END_REF] while its use could allow standardization, comparability and, after titration, an establishment of a standard curve for quantification. Positive controls can be FH-or FI-depleted NHS [START_REF] Roumenina | A prevalent C3 mutation in aHUS patients causes a direct C3 convertase gain of function[END_REF] but due to their poor reproducibility, a better choice could be a NHS spiked with blocking anti-FH antibodies against the N-terminus or C-terminus [START_REF] Frimat | Complement activation by heme as a secondary hit for atypical hemolytic uremic syndrome[END_REF].

-Which deposits are relevant to measure? Quantification of complement activation products deposits on EC surface reflects the complement over-activation or deregulation when EC are incubated with samples of interest. While C3b/iC3b deposits reflect the early steps, C5b-9 is the final product of the cascade. Thus C5b-9 deposits might be more relevant to identify a deregulation at any step. Nevertheless, an early deregulation could induce C3 activation fragments deposits without C5b-9 formation because of a TP regulation. Since they provide complementary information, both C3b and C5b-9 deposit should be measured.

-Which activation pathway? In order to assess which complement pathway is activated, the test can be performed in presence of Mg-EGTA in the serum [START_REF] Frimat | Complement activation by heme as a secondary hit for atypical hemolytic uremic syndrome[END_REF] to block CP and LP, leaving only the AP active, while EDTA blocks all three pathways. The assay can evaluate only abnormalities present in the circulation. If there is a genetic abnormality in the membrane expression of MCP in the patient for example, it cannot be detected by this test.

-How to detect and quantify deposits? Flow cytometry (FACS) [START_REF] Roumenina | A prevalent C3 mutation in aHUS patients causes a direct C3 convertase gain of function[END_REF][START_REF] Roumenina | Hyperfunctional C3 convertase leads to complement deposition on endothelial cells and contributes to atypical hemolytic uremic syndrome[END_REF][START_REF] Frimat | Complement activation by heme as a secondary hit for atypical hemolytic uremic syndrome[END_REF][START_REF] Roumenina | Complement activation in sickle cell disease: Dependence on cell density, hemolysis and modulation by hydroxyurea therapy[END_REF] and immunofluorescence (IF) [START_REF] Galbusera | An Ex Vivo Test of Complement Activation on Endothelium for Individualized Eculizumab Therapy in Hemolytic Uremic Syndrome[END_REF][START_REF] Noris | Dynamics of complement activation in aHUS and how to monitor eculizumab therapy[END_REF][START_REF] Palomo | Complement Activation and Thrombotic Microangiopathies[END_REF][START_REF] Frimat | Complement activation by heme as a secondary hit for atypical hemolytic uremic syndrome[END_REF],10] can be used for quantification. Similar results were obtained when HUVEC pre-activated with heme were incubated with NHS or aHUS patients sera [START_REF] Frimat | Complement activation by heme as a secondary hit for atypical hemolytic uremic syndrome[END_REF] or SCD patients sera [START_REF] Roumenina | Complement activation in sickle cell disease: Dependence on cell density, hemolysis and modulation by hydroxyurea therapy[END_REF]. While IF allows a direct analysis of the deposits on EC adherent on slide, FACS requires a cell detachment that may lead to a partial loss of signal.

FACS provides rapid and objective quantification. On the opposite, quantification step by IF requires a supplementary standardization to allow comparability and reproducibility. Deposits quantification by IF usually implies measurement of the area occupied by fluorescent staining in fields systematically captured on the slide and is expressed as mean of pixel 2 per field, then compared with negative control [START_REF] Galbusera | An Ex Vivo Test of Complement Activation on Endothelium for Individualized Eculizumab Therapy in Hemolytic Uremic Syndrome[END_REF][START_REF] Noris | Dynamics of complement activation in aHUS and how to monitor eculizumab therapy[END_REF][START_REF] Palomo | Complement Activation and Thrombotic Microangiopathies[END_REF][START_REF] Timmermans | C5b9 Formation on Endothelial Cells Reflects Complement Defects among Patients with Renal Thrombotic Microangiopathy and Severe Hypertension[END_REF]. Quantification of the number/density of EC on which deposits are detected or the ratio surface of the deposits area/number of nuclei might be relevant and helpful to standardize this step.

-Why complement is activated? Initially, positivity was reported in aHUS patients and their healthy relatives, carrying complement mutations [START_REF] Noris | Dynamics of complement activation in aHUS and how to monitor eculizumab therapy[END_REF][START_REF] Roumenina | A prevalent C3 mutation in aHUS patients causes a direct C3 convertase gain of function[END_REF] or in aHUS model conditions (reconstitution of FB-depleted serum with recombinant WT or mutant FB [START_REF] Roumenina | Hyperfunctional C3 convertase leads to complement deposition on endothelial cells and contributes to atypical hemolytic uremic syndrome[END_REF]). Nevertheless, aHUS patients without genetic/acquired complement abnormality, some mutation-negative healthy relatives or patients with diseases lacking complement mutations/autoantibodies were reported positive [START_REF] Palomo | Complement Activation and Thrombotic Microangiopathies[END_REF][START_REF] Timmermans | C5b9 Formation on Endothelial Cells Reflects Complement Defects among Patients with Renal Thrombotic Microangiopathy and Severe Hypertension[END_REF][START_REF] Roumenina | Complement activation in sickle cell disease: Dependence on cell density, hemolysis and modulation by hydroxyurea therapy[END_REF][START_REF] Piras | Molecular Studies and an ex vivo Complement Assay on Endothelium Highlight the Genetic Complexity of Atypical Hemolytic Uremic Syndrome: The Case of a Pedigree With a Null CD46 Variant[END_REF]. Therefore, the mechanism behind complement deposition is more complex. These individuals may have a circulating defect, resulting in complement dysregulation on the endothelium. For SCD samples, cell-free heme seems responsible for the complement activation as it can be prevented by heme scavenging with hemopexin [START_REF] Roumenina | Complement activation in sickle cell disease: Dependence on cell density, hemolysis and modulation by hydroxyurea therapy[END_REF]. The use of hemopexin or other inhibitors yet to be defined could help to distinguish the mechanism by which complement is activated, i.e. due to complement abnormality or due to activator present in the circulation. Some drugs could also act as a trigger of complement activation, as Carfilzomib which induces Thrombotic Micro-Angiopathy (TMA) [START_REF] Blasco | Complement as the enabler of carfilzomib-induced thrombotic microangiopathy[END_REF]. Therefore, this test is not specific for complement genetic/acquired abnormalities, but turns positive in a large spectrum of diseases, where complement and/or EC activating factors are present in the circulation.

-For which indications? This assay was developed for aHUS [START_REF] Roumenina | A prevalent C3 mutation in aHUS patients causes a direct C3 convertase gain of function[END_REF][START_REF] Roumenina | Hyperfunctional C3 convertase leads to complement deposition on endothelial cells and contributes to atypical hemolytic uremic syndrome[END_REF][START_REF] Frimat | Complement activation by heme as a secondary hit for atypical hemolytic uremic syndrome[END_REF], but additional studies suggest its utility to explore complement contribution to pathophysiology of other diseases, such as HELLP syndrome and pre-eclampsia [START_REF] Palomo | Complement Activation and Thrombotic Microangiopathies[END_REF], TMA associated with severe hypertension [START_REF] Timmermans | C5b9 Formation on Endothelial Cells Reflects Complement Defects among Patients with Renal Thrombotic Microangiopathy and Severe Hypertension[END_REF], SCD [START_REF] Roumenina | Complement activation in sickle cell disease: Dependence on cell density, hemolysis and modulation by hydroxyurea therapy[END_REF], Carfilzomib induced TMA [START_REF] Blasco | Complement as the enabler of carfilzomib-induced thrombotic microangiopathy[END_REF] to name a few. Finally, Galbusera et al and Palomo et al proposed the EC assay as a tool for Eculizumab therapy management in patients with aHUS [START_REF] Galbusera | An Ex Vivo Test of Complement Activation on Endothelium for Individualized Eculizumab Therapy in Hemolytic Uremic Syndrome[END_REF][START_REF] Palomo | Complement Activation and Thrombotic Microangiopathies[END_REF].

Concluding Remarks

Ex vivo complement activation assay could represent a useful tool to demonstrate complement involvement in a given disease. With the current development of complement blockers and in the field of precision medicine, it may allow to better personalize and monitor such therapeutics. Nevertheless, it first has to be well standardized in bona fide complement mediated diseases, to allow comparability and reproducibility.

Box 1: Brief overview of complement system.

As part of innate immunity, complement plays a key role in host homeostasis, inflammation and in the defense against pathogens [START_REF] Merle | Complement System Part II: Role in Immunity[END_REF]. It is composed by more than 30 soluble and membrane bound proteins, which coordinated action represents a first line of defense. It can be activated through three different pathways: the classical pathway (CP), lectin pathway (LP) or the alternative pathway (AP). When activated these serine protease cascades converge to a terminal pathway (TP), generating cleavage products as anaphylatoxins (C3a and C5a), opsonin (C3b/iC3b) and the membrane attack complex (MAC).

  CP and LP activation follows the recognition of Pathogen-Associated Molecular Patterns (PAMPS) or Danger-Associated Molecular Patterns (DAMPS) by Pattern Recognizing Molecules (PRM). Their activation is Ca-dependent and results in the formation of classical C3 convertase: C4b2a. Conversely, AP is constantly activated at low level in fluid phase and generates small quantity of C3b. C3b can bind activator surface (apopto-necrotic or bacterial) and thus initiate Mg-dependent alternative C3 convertase formation (C3bBb). Covalent bound C3b associates with FB to form AP C3 proconvertase (C3bB) and then, by FD activation, forms AP solid phase C3 convertase (C3bBb). C3bBb is a powerful enzyme that catalyzes further cleavage of C3: it is the amplification loop. To avoid self-aggression, AP is highly regulated on host cells, notably endothelial cells (EC). Main regulator, FH can compete with FB for C3b binding, is FI cofactor for C3b inactivation in iC3b and can induce C3bBb dissociation. MCP (CD46) and CR1 are others, membrane bound, FI cofactors for the inactivation of C3b to iC3b. DAF (CD55) is another membrane bound regulator implicated in AP C3 convertase dissociation. Lastly, CD59 inhibits final C9 polymerization and MAC formation. A defect in these regulators can lead to inadequate complement activation at EC surface and become a disease cause as in atypical Hemolytic and Uremic Syndrome (through anti-FH antibody, FH, FI or MCP mutations).

Figure legend Figure 1 :

 legend1 Figure legend

Acknowledgements

This work is supported by an ANR JCJC to S.C.

The authors declare no conflict of interest.


S Graetzer
email: s.n.graetzer@salford.ac.uk

A Landowska

L Harris

T J Cox

W J Davies
email: w.davies@salford.ac.uk

CONTINUOUS EVALUATIVE AND PUPIL DILATION RESPONSE TO SOUNDSCAPES

We investigated human response to soundscapes using a continuous second-by-second rating of soundscapes and a more conventional overall rating of each sample at the end of each audition. In this work, our primary aim was to explore what continuous ratings tell us about soundscape perception. Our secondary aim was to understand how pupil dilation response (i.e., changes in pupil size) relates to such perception. We used ambisonic soundscapes simulated in a laboratory environment. During playback, listeners were asked to perform a continuous evaluation on pleasantness and eventfulness dimensions.

A comparison of the results of the two rating methods (continuous and overall) indicates that the first can be used reliably for soundscape evaluation. We found a strong effect of soundscape category -human, nature or manmade industrial or domestic -on the pleasantness and eventfulness ratings and on the first two principal components derived from the overall ratings. These components related to pleasantness-eventfulness dimensions. In addition, we observed some effects of category on pupil size, which were broadly consistent with perceptual ratings. The perceived differences between soundscape categories were consistent with findings in the literature of greater pleasantness ratings for natural sounds than mechanical or industrial sounds.

INTRODUCTION

Soundscapes can be defined as acoustic environments as perceived or experienced and understood by a person or people, in context [START_REF]BS EN ISO 12913-1 Acoustics -Soundscape Part 1: Definition and conceptual framework[END_REF]. They consist of multiple sound sources and multiple sounds that may occur simultaneously or separately in time. Typically, human emotional responses are modelled as two-dimensional. For example, in Russell's circumplex model of affect [START_REF] Russell | Circumplex model of affect[END_REF], emotions evoked by an environment are represented in a two-dimensional space with axes valence (pleasure-displeasure) and arousal (arousal-sleepiness or active-passive). Västfjäll [START_REF] Västfjäll | The subjective sense of presence, emotion recognition, and experienced emotions in auditory virtual environments[END_REF] argued that this model can be applied to the context of emotions evoked by particular sounds. Axelsson et al. [START_REF] Axelsson | A principal components model of soundscape perception[END_REF] redefined the dimensions as 'pleasantness' and 'eventfulness', the latter on a continuous scale of eventfulnessuneventfulness. Davies et al. [START_REF] Davies | Soundscape reproduction and synthesis[END_REF] suggest that the weight of evidence in the literature is now sufficient for two dimensions of pleasantness/calmness and eventfulness/activity to be regarded as the standard model for the perceptual dimensions of soundscapes.

Soundscape category, like other informational properties of soundscapes, significantly contributes to soundscape perception (e.g., [START_REF] Guastavino | The ideal urban soundscape: Investigating the sound quality of french cities[END_REF]). Previous work by Bones et al. [START_REF] Bones | Sound categories: Category formation and evidence-based taxonomies[END_REF] indicated that isolated sounds were classified by listeners in a free sorting task into three high level categories: people, which was subdivided into voices and music, nature, which was subdivided into animals and weather, and manmade, which was subdivided into industrial (mechanical and transport) and household/domestic.

Pupil size has been found to change spontaneously during visual and audio stimulus presentation to reflect arousal and cognitive processes such as decision making, problem solving and language comprehension (e.g., [START_REF] Partala | Pupil size variation as an indication of affective processing[END_REF]). Previous studies of pupil dilation response to non-speech and nonmusic auditory stimuli suggests that the pupil dilates in response to louder sounds, surprising sounds vs. unsurprising sounds, sounds with high positive/negative valence vs. neutral sounds, and for active vs. passive listening (e.g., [START_REF] Partala | Pupil size variation as an indication of affective processing[END_REF]). A review of pupil dilation response to auditory stimuli is provided by Zekveld et al. [START_REF] Zekveld | The pupil dilation response to auditory stimuli: Current state of knowledge[END_REF].

AIMS AND RESEARCH QUESTIONS

In the study reported in this paper, listeners rated thirty second excerpts of soundscapes of various categories using a two-dimensional pleasantness-eventfulness model. Soundscapes were reproduced by a 16-channel loudspeaker array. Listener pupil dilation response was measured during soundscape exposure. The research questions included the following: firstly, do soundscapes associated with the categories human, nature, manmade domestic and manmade industrial differ from one another according to pleasantness (valence) and eventfulness (arousal) both on a continuous evaluation and on a more conventional soundscape evaluation performed after exposure, i.e., semantic differential scales, to the stimulus? Secondly, how do real-time pleasantness-eventfulness ratings compare to semantic differential scale ratings? Do the scale ratings have underlying dimensions of pleasantness and eventfulness on a principal component analysis? Thirdly, is there an effect of soundscape category on pupil dilation response and, by ex-tension, on arousal?

The primary aim was to investigate how soundscapes are perceived by human listeners on pleasantness and eventfulness dimensions on a continuous basis, and how this evaluation compares with a conventional semantic differential scale evaluation. A secondary aim was to understand how pupil dilation response relates to soundscape perception. Continuous subjective evaluation constitutes a new method for soundscape research. Furthermore, the use of pupillometry to measure arousal is a new method in the context of spatial audio reproduction of soundscapes.

METHOD

In the study reported in this paper, forty subjects listened to thirty second soundscape excerpts assigned to four categories -human, nature, manmade industrial and manmade domestic -while interacting with a custom MAT-LAB Graphical User Interface (GUI) [START_REF]MATLAB Version[END_REF]. Listeners subsequently completed a nine attribute semantic differential scale evaluation. Pupil size was measured during the soundscape playback and for five seconds immediately preceding playback (baseline), during which time listeners looked at a fixation point. During soundscape playback, listeners completed a continuous pleasantnesseventfulness evaluation via the GUI, while directing their gaze towards the interface.

The experiment took approximately 1.5 hours, including set up. The luminance in the room was kept constant at 2.7 EV to ensure that pupil size was not affected by changes in ambient light intensity. A light grey background was used in the GUI.

Participants

All listeners had normal hearing and normal or correctedto-normal vision by their own report. Nineteen male and twenty female listeners, and one listener identifying as other, were recruited (mean = 32.6 years, std = 6.8 years). Of these, 33 were right-handed and 7, left-handed; 34 were native English speakers, and 6 were highly fluent. All participants were dominant or native English speakers who reported that they did not use autonomic nervous system blockers, and had not used stimulants, including caffeine, within the 5 hours preceding the session.

Soundscape recordings

First order ambisonic reproduction was used after Davies et al. [START_REF] Davies | Soundscape reproduction and synthesis[END_REF]. Recordings were made using a Soundfield ST450 microphone recording to ambisonic B-format. The microphone was connected to a Soundfield ST450 MKII control unit with preamplifier connected to a Zoom H6 portable recorder in ambisonic B-format with a sampling rate of 44.1 kHz (16 bits). The soundscapes were selected so as to be dominated by three principal categories of sounds: human or people, nature and manmade where manmade was divided into industrial and domestic. In MATLAB, the ambisonic B-format signals were decoded to first-order ambisonics for a 16-channel loudspeaker array. The 16channel Genelec 8030A loudspeaker array in the audio booth consisted of eight speakers in the horizontal plane (positioned at azimuths +0°, +45°, +90°, +135°, ± 180°, -45°, -90°, -135°), 4 at +39°elevation (positioned at azimuths +45°, +90°, -45°, -135°) and 4 at -39°elevation (positioned at azimuths +45°, +135°, -45°, -135°). The speakers had a radius of 1.26 m at 0°elevation and of 1.54 m at ± 39°elevation.

The recordings were segmented into thirty second excerpts. Ten excerpts were chosen at random from each category, with the constraint that at least one excerpt must be sampled from each recording. Excerpts were equalised in loudness.

Playback

The experiment took place in an audio booth in which the background noise level at the listener position was 26 dB L Aeq and the reverberation time was approximately 0.1 s. The loudspeaker array was first calibrated such that each loudspeaker reproduced a pink noise signal at 76 dB(A) (slow integration time) at the listening position. The loudspeakers were connected via an RME Digital/Analog Interface M-32 DA and an RME Hammerfall DSP soundcard to a PC running the GUI. The GUI was implemented such that the soundscape excerpts were reproduced at a level of 65 dB L Aeq in the position of the listener, as measured with a Brüel & Kjaer (B&K) Head and Torso Simulator (HaTS) with Type 4190 microphones, connected to a B&K data acquisition unit Type 3560-B-130, connected via LAN to a PC running Pulse LabShop.

Real-time pleasantness and eventfulness ratings were measured during soundscape playback via mouse movements within a computer representation of a two-dimensional emotional space (shown in Fig. 1) after the method used previously for music and speech by Coutinho and colleagues [START_REF] Coutinho | Psychoacoustic cues to emotion in speech prosody and music[END_REF]. The labelling of the dimensions and the descriptors at the corners of the space -'exciting', 'calm', 'monotonous' and 'chaotic' -derive from Axelsson and colleagues' pleasantness-eventfulness model (see [START_REF] Axelsson | A principal components model of soundscape perception[END_REF], Figure 4, p. 2844). The data were collected with a 10 Hz sampling rate. The forty soundscape excerpts were presented in a pseudo-random order to each listener.

Tasks

As part of the training stage, participants were given anchor stimuli for each of the four extremes of the twodimensional space and given the opportunity to practice. Participants were shown the interface and instructed to "rate the soundscapes according to your perception of pleasantness and eventfulness. You can move the mouse anywhere you like within the four quadrants to reflect your perception. If your perception changes, move the mouse to reflect this change." The initial cursor position was at the centre of the four quadrants. After listening to each soundscape excerpt, the listeners were asked to rate the entire excerpt on nine visual analogue scales from 0, 'not at all', to 100, 'extremely'. The scale attributes were pleasant, chaotic, vibrant, uneventful, calm, annoying, eventful, monotonous, and unpleasant [START_REF]1 Acoustics -Soundscape Part 2: Data collection and reporting requirements[END_REF]. After listening to the soundscape excerpt, the listeners were asked to rate the entire excerpt.

Pupillometry

The Pupil Labs [START_REF] Kassner | Pupil: An open source platform for pervasive eye tracking and mobile gaze-based interaction[END_REF] head-mounted, video-based eyetracking device used in this study comprised a high-speed optical camera and two global shutter infra-red (IR) cameras with IR illumination. These had a resolution of 200 x 200 pixels at 124 frames per second. Data were captured and initially processed via Pupil Capture and Pupil Player v. 1.12-17 [START_REF] Kassner | Pupil: An open source platform for pervasive eye tracking and mobile gaze-based interaction[END_REF].

Signal processing

Non-pupillometric signals were processed with MATLAB v2019b [START_REF]MATLAB Version[END_REF]. Post-processing and statistical analysis was conducted in MATLAB and R v. 3.5.3 [START_REF]R: a language and environment for statistical computing[END_REF].

Pupillometric data were captured and processed using Pupil Labs (Germany) Pupil Capture software v. 1.12-17 [START_REF] Kassner | Pupil: An open source platform for pervasive eye tracking and mobile gaze-based interaction[END_REF] and post-processed in MATLAB using the Kret and Sjak-Shie [START_REF] Kret | Preprocessing pupil size data: Guidelines and code[END_REF] method. After processing, signals were normalised by subtracting the baseline from the PDR on a trial-by-trial basis. A Generalised Additive Mixture Model (GAMM [START_REF] Van Rij | Analyzing the time course of pupillometric data[END_REF]) was used for statistical analysis.

RESULTS

Continuous ratings

Continuous ratings indicated that median pleasantness was highest for nature, lowest for the manmade categories, and intermediate for the human category (Fig. 2). Eventfulness tended to be higher for the human category than the other categories. Nature was primarily associated with the pleasant eventful quadrant, while manmade domestic was primarily associated with the unpleasant eventful quadrant.

A mixed-effects linear regression model with response variable, pleasantness, predictor variables, time (s), category (with reference level, human), and an interaction of time and category, and random effects listener and stimulus, indicated that nature was associated with higher pleasantness than human (B = 0.22, SE = 0.05, t = 4.58, p < 0.0001), and that there was a main effect of time, such that pleasantness decreased very slightly as time passed (B = -0.0005, SE = 0, t = -8.67, p < 0.0001).

There was an interaction of category and time such that the nature category was associated with an increase in pleasantness over time relative to the human category, while the manmade categories were associated with a decrease, with the difference emerging within the first five seconds (nature∼human, B = 0.012, SE = 0.0, t = 76.85, p < 0.0001; industrial∼human, B = -0.01, SE = 0.0, t = -47.46, p < 0.0001; domestic∼human, B = -0.01, SE = 0.0, t = -56.45, p < 0.0001). R 2 = 0.47.

A mixed-effects linear regression model with the same fixed and random effects for real-time ratings of eventfulness indicated that there were main effects of time such that eventfulness increased slightly as time passed, as might be expected as events accumulate (B = 0.01, SE = 0, t = 49.77, p < 0.0001). There was an interaction of category and time such that the human category was associated with higher eventfulness ratings than the other categories, with the difference emerging within the first five seconds (nature∼human, B = -0.01, SE = 0.0, t = -30.23, p < 0.0001; industrial∼human, B = -0.01, SE = 0.0, t = -43.07, p < 0.0001; domestic∼human, B = -0.005, SE = 0.0, t = -7.21, p < 0.0001). R 2 = 0.25. In both models, the manmade categories did not differ from one another.

Conventional post-stimulus ratings

Immediately after playback, soundscapes were evaluated on nine attributes: pleasant, chaotic, vibrant, uneventful, calm, annoying, eventful, monotonous, and unpleasant (Fig. 3). The nature category was associated with greater scores on pleasant and calm attributes, and lower scores on chaotic, annoying, monotonous and unpleasant attributes than other categories. While on many attributes the manmade subcategories did not differ markedly, the industrial category was rated as being less eventful than all other categories, and the domestic category was rated as being more vibrant and less monotonous than the industrial category.

For the 40 soundscape excerpts, the first two principal components explained 43 and 29% of the variability (72% in total). PC1 was inversely related to pleasantness and PC2 to eventfulness. The results indicated that attributes unpleasant and annoying are synonymous in the context of the study. PC3 explained only 7.5% of the variance, and PC4, 5.8%. Linear mixed-effects models of PCs 1 and 2 were run with category as a fixed predictor (reference level: human) and ID and stimulus as random effects. There was an effect of category on pleasantness (likelihood ratio test statistic, lrt = 75.49, p < 0.0001): the human category was associated with lower pleasantness than the nature category but higher pleasantness than the manmade categories. The nature category was associated with higher pleasantness than the manmade categories, which did not differ from one another. There was an effect of category on PC2, or eventfulness (lrt = 8.20, p < 0.05): the human category was associated with higher eventfulness than the manmade industrial category. The nature and domestic categories were similarly eventful.

Pupil dilation response

Pupil dilation response over time is shown per soundscape category in Fig. 4. The human category is associated with a slight constriction relative to baseline but the least average constriction, with early peaks. The nature category is associated with pupil constriction relative to baseline, which suggests a decrease in arousal. The manmade industrial category is associated with the greatest constriction relative to baseline. This is consistent with the finding that the industrial stimuli were rated as less eventful than others. A GAMM [START_REF] Van Rij | Analyzing the time course of pupillometric data[END_REF] indicated that the human category was associated with greater pupil dilation relative to baseline than the industrial category (B = -0.05, SE = 0.02, t = -2.30, p < 0.05), and there was a tendency for the human category to be associated with greater pupil dilation relative to baseline than the domestic category (B = -0.05, SE = 0.02, t = -1.95, p = 0.051). However, there was no reliable difference between the human and nature categories (p = 0.2). The model explained 84.5% of the deviance.

DISCUSSION

In this study, it was confirmed that soundscapes of the categories human, nature and manmade differ from one another in perceived pleasantness and eventfulness on a real-time, continuous evaluation, on a conventional poststimulus semantic differential scale evaluation, and on a pupil dilation response evaluation.

Continuous ratings

The nature category was associated with higher real-time pleasantness ratings than the human category across the time course, while the manmade categories tended to be associated with lower pleasantness ratings. Pleasantness ratings decreased slightly as time passed, perhaps due to de-sensitisation. Within the first two seconds of playback, the difference in pleasantness between the nature and 10.48465/fa.2020.0962 other categories emerged. The human category tended to be rated as more eventful than the other categories, perhaps partly due to the number of talkers in the 'crowd' scenes. The lack of differentiation between the manmade categories on both pleasantness and eventfulness supports the claim of Bones et al. [START_REF] Bones | Sound categories: Category formation and evidence-based taxonomies[END_REF] that these are subordinate categories of a higher order 'manmade' category. The findings that nature sounds are more pleasant than manmade/technological sounds and that human sounds, such as voices, tend to be perceived as more pleasant than manmade sounds, but not as pleasant as nature sounds, are consistent with the literature (e.g., [START_REF] Guastavino | The ideal urban soundscape: Investigating the sound quality of french cities[END_REF]).

A model of real-time eventfulness ratings with predictors soundscape category and time (s) explained a smaller proportion of variance (25%) than a model of real-time pleasantness ratings with the same predictors (47%). This could be primarily because perception of eventfulness is more explained than perception of pleasantness by personal factors that were not modelled, such as personal preferences and sensibility, and previous experiences and expectations. Secondarily, it could be that the concept of 'eventfulness' is more ambiguous than the concept of pleasantness. If so, in future, a less ambiguous term might be used.

Conventional post-stimulus ratings

Soundscapes were evaluated after playback on nine attributes: pleasant, chaotic, vibrant, uneventful, calm, annoying, eventful, monotonous, and unpleasant. Overall, the results indicated that unpleasant and annoying are (nearly) synonymous in the present context, which is consistent with the recommendations in PD ISO/TS 12913 2:2018 [START_REF]1 Acoustics -Soundscape Part 2: Data collection and reporting requirements[END_REF]. 72% of the variability was explained by two principal components corresponding inversely to pleasantness and eventfulness. It was therefore confirmed that the scale ratings have underlying dimensions of pleasantness and eventfulness on a principal component analysis. Soundscape category was found to predict both of these principal components.

Ratings on the pleasant attribute were highest for the nature category, lowest for the manmade categories, and intermediate for the human category. The nature category was rated as least chaotic, monotonous and unpleasant, and most calm. On many attributes, the manmade categories were not well distinguished. The finding that the human category tended to be associated with higher eventfulness than the manmade industrial category is likely because the human soundscapes involved crowd scenes, while the industrial soundscapes involved fewer sound sources, such as a small number of people working in an acoustic laboratory with intermittent ventilation.

Pupil dilation response

There was some evidence of an effect of soundscape category on pupil dilation response. The nature category was associated with pupil constriction relative to baseline, suggesting decreased arousal. This is consistent with ratings on the calm and chaotic attributes. The human category was associated with only a small amount of constriction. There was little evidence of a difference between the manmade categories, as was the case on several semantic differential scale attributes. Overall, the results were consistent with the ratings on the eventful attribute, which supports the argument that eventfulness is closely related to arousal, which is reflected in pupil dilation.

CONCLUSIONS

The broad aim of the present study was to investigate human perception of soundscapes, including emotional response, while controlling for the overall soundscape loudness. Evidence has been provided that the sound categories human, nature and manmade, as proposed by Bones et al. [START_REF] Bones | Sound categories: Category formation and evidence-based taxonomies[END_REF], hold for complex audio in the form of soundscapes in addition to isolated sounds. These categories can be distinguished on the basis of pleasantness and eventfulness ratings. The results of a real-time continuous evaluation of soundscapes on dimensions pleasantness and eventfulness were consistent with the results of a principal components analysis of semantic differential scales derived from PD ISO/TS 12913-2 [START_REF]1 Acoustics -Soundscape Part 2: Data collection and reporting requirements[END_REF]. The finding of least pupil dilation relative to baseline for the industrial category vs. other categories is consistent with the rating of these stimuli as least eventful.

Figure 1 .

 1 Figure 1. Two-dimensional display for real-time soundscape evaluation.

Figure 2 .

 2 Figure 2. Trajectories of real-time pleasantness (upper panel) and eventfulness (lower panel) ratings by category, averaged over listeners.

Figure 3 .

 3 Figure 3. Bar plot of mean ratings on nine attributes by category with standard error bars (95% confidence intervals).

Figure 4 .

 4 Figure 4. Pupil dilation response over time per soundscape category.

10.48465/fa.2020.0962

e-Forum Acusticum, December 7-11, 2020


Minami Arai

Kanako Ueno

Study on sound environment and operational measures in temporary school buildings

In Japan, an increasing number of schools are being rebuilt owing to problems such as decrepitude and weak seismic capacity. During the reconstruction process, temporary school buildings are often erected using a prefabricated structure. Such temporary school buildings lack acoustical performance and are exposed to construction noise. This study investigates the actual condition of these buildings, using the case of a temporary school building of an elementary school in Tokyo, and examines the possibility of improvement and countermeasures that could be taken in the operational scene. First, to investigate the actual situation, an acoustic measurement in the classroom and a questionnaire survey of teachers and children were conducted. Second, to address the problems caused by noise, small spaces were installed in the classroom and the sick room, so that children could relax in a quiet environment. In addition, sound-absorbing material was experimentally set up on the ceiling of the classroom. The study investigated the effectiveness of these measures by conducting an interview survey of teachers, and a questionnaire survey of both teachers and children.

INTRODUCTION

In Japan, several schools are being rebuilt owing to problems such as decrepitude, and weak seismic capacity. During the reconstruction process, temporary school buildings are often erected using a prefabricated structure. Such buildings lack acoustical performance, and are exposed to construction noises. In recent years, there has been an increase in the number of children reported with (or suspected to have) developmental disabilities in schools. In particular, children with autistic spectrum disorder often have atypical sensorial characteristics [START_REF] Hazen | Sensory symptoms in autism spectrum disorders[END_REF]. From the perspective of inclusive education, it is essential to improve the environment for children who need special support. Here, the temporary school buildings can lead to a more problematic environment for these children during the reconstruction process.

Considering the facts mentioned above, we investigated the sound environment in the temporary school building of an elementary school in Tokyo, and examined the possibility of improvement by operational measures that could be taken during use. Firstly, an acoustic measurement of the classroom, and a questionnaire survey on teachers and students were conducted. Secondly, to improve the problems caused by noise, small spaces were installed in both classrooms and a sick room so that children can relax in a quiet environment. In addition, sound-absorbing material was experimentally set up on the ceiling of the classroom. The study investigated the effectiveness of these measures by conducting an interview survey of teachers, and a questionnaire survey of both teachers and students.

SOUND ENVIRONMENT IN THE CLASSROOM

The target school was routinely exposed to noise owing to the construction of a new building in the schoolyard (Figure 1). The influence of construction noise during classes is considered to be very large because the windows of 11 (out of 15) classrooms are closely facing to the construction site (Table 1, Figure 2). The background noise was measured using a sound level meter (RION, NL-42) which was set 40 cm under the ceiling of a classroom that faced the construction site (Figure 3). These data were measured under uncertain conditions such as with the door open or closed. The frequency distribution of the equivalent A-weighted sound pressure level for 1 min (LAeq, 1min) on weekdays (11 class hours) when the classroom was unoccupied, and on Saturday when the school was closed is shown in Figure 4. This indicated that the LAeq, 1min values of weekdays were higher than those of Saturday probably due to the influence of sounds from surrounding classrooms. A recommended sound level in the classroom was defined to be less than or equal to 40 according to the environmental standards of the Architectural Institute of Japan [START_REF]Architectural Institute of Japan: AIJES-S001-2008, Academic Standard and Design Guidelines for Sound Environment in School Buildings[END_REF], and less than or equal to 50 according to School Environmental Health Standards [3]. Almost all measurement results exceeded 40 dB. For approximately 90 % of the time on weekdays and approximately 60 % of the time on Saturday exceeded 50 dB.

With regard to the sound environment during classes, Aweighted sound pressure level for 1 s (LAeq, 1s) in the classroom is shown along with the class activities (Figure 5). It was 60--80 dB during the teacher's instruction, and 70-80 dB during children's discussion. In writing work, despite the small sound generated in the classroom, the LAeq, 1s was 60-70 owing to the construction noise. This suggested that the environment was inferior in both aspects of listening (S/N ratio), and noise exposure.

USERS' EVALUATION

Outline

The outline of the questionnaire survey that was conducted for students (3 rd -6 th grade), and teachers to investigate the users' evaluation of the sound environment in the classroom is shown in Table 2. The responses were obtained from a high percentage of the targeted students (91 %) and teachers (100 %).

Evaluation of Teachers

The subjects of the questionnaire survey were the homeroom teachers. The questions were about the sound environment of the classrooms in the temporary school building. As shown in Figure 6 (a), more than 70 % of the teachers answered "be concerned / tend to be concerned" to the question of "Are you concerned about the sounds around you during classes?". More than 60 % of the teachers pointed out that they "feel / tend to feel" the difficulty while teaching (Figure 7). Therefore, influence of the sound environment on class management was considered to be severe. In addition, results of asking for answers about sounds in the frequent order are shown (Figure 9 (a)). A half of the total number of teachers pointed out the construction noise first. Considerable number of teachers pointed out the sounds from surrounding classrooms on the same floor, upper floors, and corridors. From the results, the sound insulation performance between the classrooms and the floor was supposed to be insufficient. Moreover, approximately a half of the teachers pointed out the sound generated within the classroom.

Evaluation of Students

The subjects of the questionnaire survey were students ranging from 3 rd grade to 6 th grade. As shown in Figure 6 (b), 80 % of the children answered "very often /often / sometimes" to the question of "Are you concerned about the sounds around you during classes?", and 60 % of the students answered that they were "difficult to concentrate" when they were concerned about the sounds (Figure 8). The influence of noise on their learning was considered to be large. In addition, 65 % of the students answered that they are concerned the construction noise (Figure 9 (b(i)). The construction noise was more frequently selected by 5 th and 6 th grades students probably because all of their classrooms were adjacent to the construction site. A comparison between the results of classes that did not face the construction site (2 out of 11 classes subject to questionnaire survey), and classes that faced the construction site (9 classes) is shown in Figure 9 (b(ii)). 40 % who were from classes that did not face the construction site selected the construction noise. However, over 70 % who were from classes that faced the construction site selected it. Besides, there were many responses such as "the sound on upper floor" from 6 th grade students whose classroom was located on the second floor. As a result, it was confirmed that construction noise and sounds from surrounding classrooms and corridors affected the concentration and listening of children.

TRIALS FOR IMPROVEMENT

Installation of Relaxing Space

Outline

In our previous study, a small calming space that was composed of a sound absorbing material inside, was introduced to provide a calm environment, and was installed in special-needs education classrooms. During break time, it was observed that autistic children used this space as a place where they could calm down and suppress panic [4]. In this paper, we have proposed "a relax box" which can be used on a desk because there was no extra room within the classroom of the school under investigation.

During the preliminary opportunity to introduce the "relax box" (Figure 10(a)) to the teachers, many requested that they would like to use it in their own classrooms as a place to escape from daily noisy environment. Therefore, we contrived a material kit so that anyone can easily make the "relax box." The relax box was made of a corrugated cardboard box. A cushion-like sound absorbing material (POLYWOOL, 30 mm, Fukoku Co., Ltd.) was wrapped with nonwoven fabric and was attached on the inner side of the box except the bottom surface. A sound absorbing material (TAFNEL, Mitsui Chemicals, Inc.) was attached on top of the opening. A 5 mm urethane mat was overlaid on the bottom of box. The size was set so that it could be placed on a desk and used by allowing In addition, in the sick room, (set by a mat on the floor), the relax box and a small calming space, and a cushion were placed (relaxing space, Figure 11(b)). A small calming space is the size that the whole body of a child can enter when one sits on the floor by holding the knee (W 60 × D 63 × H 83 cm 3 , Figure 10(b)). It is a box made of plywood with opening on one side (15 mm). Similar to the relax box, it was set up using a cushion-like soundabsorbing material wrapped with nonwoven fabric on the inner side and upper surface, and a cloth-like sound absorbing material was hanged to the opening.

Questionnaire and interview surveys were conducted with teachers and a school nurse to confirm the usage and to user's evaluation.

Sound Insulation Performance

The sound insulation performance of the relax box and the small calming space was measured. A pink noise was emitted from the sound source loudspeaker (Yamaha, MSR5 STUDIO), and a microphone of a sound level meter (RION, NL-42) was placed at a sound receiving point of 1.4 m from the sound source. The measurement was performed under five conditions: without the relax box/ small calming space, set the front side (open and closed)/ side/back side of the box toward the sound source side.

The relative sound pressure level to the condition without the relax box is shown in Figure 12 (a). As for the sounds from the side and the back, a larger decrease was obtained in the higher frequency range. In the 1 kHz band, a decrease of approximately 10 dB was confirmed.

For the measurement of the small calming space, a size of W 53 × D 70 × H 90 cm 3 was used. Similar to the relax box, the decrease was larger in the higher frequency range. As for the sounds from the side and the back in the 1 kHz band, a decrease of approximately 15-20 dB was confirmed (Figure 12(b)).

Using situation and efficacy

In Table 3, the results of questionnaires and interview surveys on user situations and users' comments are shown. The use of the relax box was observed in the two classes of 1 st and 6 th grade. In the 1 st grade class, it was used by five specific children when the class became noisy or when the children got tired and were unable to concentrate. In the 6 th grade class, it was confirmed that the relax box became a gathering spot during the break time and it functioned as a place to stay. In addition, the homeroom teacher of the 6 th grade class stated that he required it and was very grateful because there were both, children who generated noise, and caused panic, and moreover, the sound of the construction was noisy. With regard to the size of the relax box, it was found to be appropriate for all users.

In the sick room, we asked a school nurse to record the utilization of the small calming space. According to the records for 14 days, an average of approximately 4 children used the space per day. The largest number of children who used the space was 11 on a day. Approximately in 80 % of the cases, the children used the space for a period of less than 10 min, and 20 % used it for more than 10 min. There was a case when a child used it twice a day. According to the school nurse, the actual use was more frequent than the records because she sometimes could not record the use in a busy situation. The results of the questionnaire and the interview survey showed that approximately 10 children used it once or twice each week, and children who were sensitive to noisy sounds entered 1 st grade The children used relax box when they were fatigued, unable to concentrate, or a classroom became noisy.

Children with acoustic hypersensitivity used relax box.

In relax box, children appeared to calm down and came out after a while. Children reacted to it as a very good space in order to calm down.

th grade

For a child who became emotional, I have promoted the use of relax box. The child calmed down after crying out loudly in the box though the effect of the relax box is unknown.

I required it and was very grateful because there were both, children who generated noise and caused panic, and moreover, the sound of the construction was noisy.

Sick room

A child sensitive to noises used small calming space until the child felt better or calmed down.

I found that even a small box (small calming space) could become a relaxing place. the small calming space and used it until they felt better or they became calm.

Table 3. Use situation and comment by users of the relax box and the relaxing space

The school nurse commented that even a small box (small calming space) could become a relaxing place. On the other hand, while children visited the sick room, occasionally they looked into the small calming space while other children were using it, therefore, the necessity of setting rules for using the room was mentioned as a feedback for improvement.

Installation of Sound-absorbing Material on the Ceiling of a Classroom

Outline

For the purpose of improving the sound environment in the classroom, a cloth-like sound absorbing material (TAFNEL , Mitsui Chemical Inc.) was installed on the ceiling of the classroom (Figure 13). The area of the installation of sound absorbing material was equivalent to approximately 60 % of the ceiling area. The effectiveness was investigated by measuring the sound level in the classroom, and conducting a questionnaire survey on students, and questionnaire and interview survey on the homeroom teacher of the experimental classroom.

Result

Figure 14 shows the reverberation time measured before and after the installation of the sound-absorbing material. The average value of 500 Hz and 1 kHz band decreased from 0.51 to 0.36 s. It was shown that the original reverberation time was short though the classroom had no sound-absorbing materials as architectural finishes. The reason is supposed to be the effect of relatively thick curtain at the window. A comparison of the average values of equivalent continuous A-weighted sound pressure level for 1 min (LAeq, 1 min) in the classroom is shown in Figure 15, and was measured for 10 min during the lunch time (12: 35-12: 45). Although the values varied by day, it was confirmed that average values of before and after installation decreased by approximately 5 dB for four days.

Table 4 shows the results of interview with the teacher regarding the change before and after the installation of the sound-absorbing material. He commented that he felt a great change at first, which further indicated that the subjective change was considerably clear though the change of reverberation time was small. In addition, he reported that it became difficult for the voice to pass by, and that he had to speak louder than before, however it was not a big problem because he got used to it gradually. Besides, it was pointed out that the sound of the classroom was suppressed and the noisy condition had changed. The positive comments shown with asterisk (*) in Table 3 indicate that change had a great contribution on the learning environment.

In Figures 16 and17, the evaluation of the questionnaire survey performed on students (N=37), which was conducted 3 weeks after the installation is shown. The questionnaire was about the environmental changes owing to the installation of sound-absorbing materials. During the evaluation of sound, approximately half of the students answered that they became less affected by the I felt a great change at first. At first, children were confused by the change and there were children who said, "I have pain in my ears," and "I have difficulty to listen to the voice.", but children got used to it in the following week.

The voice became difficult to pass by and I had to speak louder than before, however, it was not a big problem because I got used to it gradually. Other teachers also commented that they used more energy while conducting the class. Meanwhile, responses such as the discomfort feeling in the ears, and the difficulty to listen to the sound were also obtained. The sound-absorbing material is considered to have suppressed the sound in the classroom significantly, and these sudden changes in the classroom environment affected the children. On this point, the homeroom teacher commented that, a few children complained of change and discomfort at first, however, they got used to it in the following week. As for the evaluations other than sound, many claims on narrowness, air quality and heat condition seemed to be constant claim for the prefabricated construction of classrooms.

To confirm the overall evaluation of the sound-absorbing material installation, a questionnaire was again conducted on the students after two months of installation. Regarding the changes in the sound environment due to the installation of the sound-absorbing material in five steps, nearly half of the children answered that "it became better." In the free description, there were opinions such as " the sound of construction became less concerned", and "the voices of friends and teachers became hard to listen." That is, a positive evaluation related to noise suppression, and a negative evaluation related to voice transmission were confirmed.

CONCLUSION

An investigation of the actual condition in temporary school buildings showed that daily construction noises and sounds from the surrounding classrooms had a significant influence on teachers and students. As a countermeasure for improvement, a relaxation space was introduced with the aim of ensuring a calm environment and was used as a place to calm children down. From the trial of installing sound absorbing materials on the ceiling of the classroom, it was confirmed that the effects of construction noise were mitigated, though there was a problem with voice transmission.

Floor 1 Figure 1 .Figure 2 .

 112 Figure 1. Construction site viewed from the window of a corridor on the third floor

FigureFigure 5 .

 5 Figure 3. Classroom where measurement was taken

Figure 7 .Figure 8 .Figure 9 .

 789 Figure 7. Result of the question on teachers(N=15): "Do you feel the difficulty in the class due to the surrounding sounds?"

  Figure 10. Use image

Figure

  Figure 13. State of classroom after installation of sound-absorbing material

Figure 17 .

 17 Figure 15. Change of sound pressure level (LAeq,1min) in classroom

Table

. Schoolroom arrangement in the temporary school building

	Construction site
	(new school building)
	Temporary
	school
	building
	10.48465/fa.2020.0297

Table 2 . Outline of questionnaire responses

 2

	0	20	40	60		80	100 100 (%)
			0	20	40	60	80	100

e-Forum Acusticum, December 7-11, 2020

10.48465/fa.2020.0297

ACKNOWLEDGEMENTS

We wish to express our sincere gratitude to the teachers and children of the research target school for their cooperation during this experiment.


Margret Sibylle Engel

Julio Herrmann

Júlio Otávio

Paulo Henrique

Trombetta Zannin
email: zannin@upfr.br

ASSESSMENT OF THE SOUND QUALITY OF CLASSROOMS THROUGH SPEECH TRANSMISSION INDEX (STI), SOUND DEFINITION (D50) AND REVERBERATION TIME (RT)

Assessment of the sound quality of classrooms through

Speech Transmission Index (STI), Sound Definition (D50) and Reverberation Time (RT)

INTRODUCTION

The learning process depends on several elements such as lecturer, student, didactic material, environment, climate, among others. Educational institutions must offer proper physical spaces to the development of activities. The acoustic quality of the teaching place is one of the variables that strongly influence students' learning. Unfavourable acoustic conditions make learning activities exhausting [START_REF] Hagen | Acoustic school easing[END_REF] Speech consists of a succession of sounds that vary rapidly from moment to moment in intensity and frequency [START_REF] Long | Architectural Acoustic[END_REF]. Speech intelligibility is described by Long [START_REF] French | Factor Governing the Intelligibility of Speech Sound[END_REF] as a method of direct measurement of the understanding of the fraction of words or sentences by a listener. Hongisto, Keranen and Larm [START_REF] Hongisto | Simple model for acoustical design of open-plan offices[END_REF] describe two main ways of calculating speech intelligibility. The audiological method, described in the American National Standards Institute (ANSI) S12.6 [START_REF]PART 1: Acoustical Performance Design Requirements, and guidelines for Schools, Part 1[END_REF], introduces the speech intelligibility index (SII) or articulation index (AI). The modulation transfer function (MTF) method, described in IEC 60268-16: 2011 [START_REF]Sound system equipment -Part 16: Objective rating of speech intelligibility by speech transmission index[END_REF], introduces the speech transmission index (STI). According to Lazarus et al. [START_REF] Lazarus | Akustische Grundlagen sprachlicher kommunikation[END_REF], STI is one of the most comprehensive and important speech intelligibility parameters. The index takes into account most conditions that can cause deterioration of speech intelligibility, such as reverberation time and background noise. This work aims to analyze the acoustic quality with which the teachers' discourse reaches students, to verify the speech intelligibility linked to the classrooms through the impulsive methods STI, RT and D50. In cases where low intelligibility was observed, simulations with material changes are proposed to correct the environment in terms of acoustics.

METHODOLOGY

The present work contemplates two stages: the first consists of collecting data through sound measurements and the second in mathematical modelling using the ODEON 11.00 combined software.

Study Area and data collection procedure

In the data collection stage, measurements of STI, RT and D50 were carried out in the classrooms of the two buildings at the Polytechnic Center of UFPR. One of the buildings was built in the 1960s, and the investigated classrooms were PG03, PG 04, PG05, PG06, PG07 and PG 15. The second building is from the Exact Sciences sector and was built in 2016, where the investigated classrooms were PA01, PA03 PA05 and PA06. This stage was carried out in periods when the rooms were not being used for class (Fig. 1). Most of the measurements took place on Saturday afternoons, so there was no interference of students during the measurement period. Birds, as well as distant horn and aeroplane sounds, were the external background sounds present during the recordings. These sounds were considered for mathematical modelling. The STI measurements were collected using the artificial mouth always in the same position: simulating a lecturer standing on the classroom stage at the height of 1.50 m. The sound level meter, on the other hand, was moved throughout the classroom, in places where students usually sit to watch classes at the height of 1.20 m. The stimuli was a MLS signal, with male filter and 1.37 seconds length.

For the RT and D50 measurements, the same equipment heights and positions from the STI measurements were adopted. The stimulus was an e-sweep with 2.73 seconds length.

Equipment used in the data collection

In the STI measurements, a computer installed with the software Dirac 3.1 (B&K 7841), a sound card (RME Fireface 800), a sound pressure meter (B&K 2260), an equalizer (Behringer FBQ 800), an amplifier (Lab Gruppen LAB 300) and an artificial mouth (directional speaker B&K 4227) were used. For the measurement of the RT, the same equipment was used with small changes. Instead of an equalizer and an artificial mouth, it was used a dodecahedral loudspeaker (omnidirectional loudspeaker) as a sound source.

Mathematical modelling

First, the classrooms were built in a virtual environment, using SketchUp software. The classrooms already assembled and with their layers (ceiling, floor, windows, tables, seats, etc.) were finally exported to ODEON 11.00. Classroom dimensions can be observed in Table 1.

RESULTS

The STI results with male filter are showing that for the old building with PVC ceiling, some classrooms are perfectly calibrated (PG05 and PG15) with similar results between measurements and simulations. In PG03 and PG04 the measurements presented greater results and in PG06 and PG07 the simulations are showing greater results. Regarding speech intelligibility, the classroom with best results was PG05 both for measurements and simulations, with values around 0.75 which is considered an excellent STI. Coincidentally this classroom has the smallest volume compared to the other classrooms with denomination "PG", which presented fair STI averages between 0.4 and 0.6. Another critical factor is the ceiling material of this classroom, which is one of the left classrooms with the original ceiling (Celotex M1), the other "PG" classrooms changed the ceiling material to PVC on a refurbishment in the recent years.

Regarding the STI values distribution, PG15 and PG04 concentrated the results in the first quartile (orange colour) and the other classrooms in the third quartile (grey colour). In the new building with Thermatex acoustic ceiling, it is observed that PA01 presented more remarkable results in the measurements and the other classrooms with denomination "PA" are showing greater results in the simulations. All classroom are classified as with a good speech intelligibility, due to STI values between 0.6 and 0.75. In the classroom with greater volumes, PA01 and PA03, the STI values presented greater variance. In PA03 the variance of STI values occurred in the third quartile (grey colour) (Figure 1). As observed in the STI averages with male filter, a similar physical behaviour was observed regarding sound definition (D50). In the old building, the greatest values are presented in the classroom PG05, with values between 0.75 and 0.85 and in the new building in PA01, with average values between 0.65 and 0.75. All other classrooms from the old building showed values under 0.6, and in the new building, the average vales are under 0.75. Regarding the averages values distribution in the old building, the majority of the classrooms presents values in the third quartile, with the exception of the classroom PG04. In the new building averages distribution concentrated in the third quartile. The first quartile was highlighted in PG05 at 500 Hz -2 KHz, PG15 at 500 Hz, and in PG07 at 500Hz and 1 kHz. For the new building, values in the first quartile were highlighted in PA05 at 1kHz and 2 Khz, PA01 and PA03 at 2kH (Figure 3).

DISCUSSION

As observed in the average measured values of STI, D50 and T30, the PG05 room has the best speech intelligibility, sound definition and reverberation time and, consequently, is the best of the environments analyzed for good learning. It is not by chance that it is the only classroom in the named "PG" classrooms, of the building from the 60s, which maintained the original acoustic ceiling. It represents the acoustics that the classrooms of the building of the 60's should have before the alterations of the original acoustic ceiling by a PVC ceiling.

The standard adopted for measurement, IEC 60268-16: 2011, suggests in its Annex G that the STI value for classrooms should be above 0.62. This reference, further demonstrates the lack of quality of the rooms PG03, PG04, PG06, PG07 and PG15, all of the old construction. In contrast, the rooms in the most recent building and PG05 are within the standard's suggestion for specific application in classrooms.

CONCLUSION

This work aimed to analyze the acoustic quality with which the teachers' discourse reaches students, to verify the speech intelligibility linked to the classrooms through the impulsive methods STI, TR and D50.

The findings of the acoustic evaluation and modeling indicated that the exchange of the acoustic ceiling for a PVC ceiling in the older rooms of the Polytechnic Center impaired speech transmission in the classrooms, being confirmed through the results obtained in the simulations carried out. Therefore, it is recommended that UFPR resume the coating to reestablish the acoustic quality of the rooms.

It is important to search for sound-absorbing materials with great coefficients during the maintenance and refurbishment of classrooms. The reduction of classroom volumes or either by lowering ceilings -facilitating the installation of acoustic ceilings -or by raising the floor, like the platforms, are options for the improvement of classrooms acoustic.

Figure 1 .

 1 Figure 1. Measurements campaign

Figure 2 .

 2 Figure 2. Male STI averages of measurements and simulations in classrooms with PVC ceiling (PG classrooms excluding PG05), Celotex M1 ceiling (PG05) and Thermatex ceiling (PA classrooms)

Figure 3 .

 3 Figure 3. D50 averages of measurements in classrooms with PVC ceiling (PG classrooms excluding PG05), Celotex M1 ceiling (PG05) and Thermatex ceiling (PA classrooms) Regarding T30, small reverberation time averages are observed in PG05 at the old building, with values under 0.5s and in the classroom PA01 of the new building with average values bellow 0.8 s. The greatest average values of T30, indicating a worst acoustic condition are shown in PG07 of the old building. Average values distributed in the first quartile are normally observed in PG 05, PA 06 and PA01. At 500 Hz values distributed in the first quartile are observed in PA06. At 1kHz the first quartile values distribution is highlighted in PG15, PG04 and PG06, as as in PA03. At 2 kHz the first quartile vales distribution were observed in PG05, PG03 and PG06 in the old building, and in PA05, PA01 and PA03 in the new building.

Figure 4 .

 4 Figure 4. T30 averages of measurements in classrooms with PVC ceiling (PG classrooms excluding PG05), Celotex M1 ceiling (PG05) and Thermatex ceiling (PA classrooms)

Table 1 .

 1 Classrooms dimensions

	Ceiling	Classroo	Length	Width	Height	Volume
	material	m	[m]	[m]	[m]	[m 3 ]
	PVC	PG03	7.45	11.3	4.07	322
	PVC	PG04	7.5	11.46	3.44	286
	Celotex	PG05	7.47	7.15 -	3.4	131
	M1		-	3.65
			3.20
	PVC	PG06	7.45	11.3	4.07	330
	PVC	PG07	10.12 11.24	3.16	396
					-
					4.10
	PVC	PG15	7.47	10.82	2.85	285
					-
					4.40
	Thermotex	PA01	6.8	11	2.64	197
	Thermotex	PA03	6.8	12.34	2.75	234
	Thermotex	PA05	6.9	10.29	2.75	195
	Thermotex	PA06	6.9	7.24	2.64	132
	The absorption coefficients for the ceiling materials are
	observed in

Table 2 .Table 2 .

 22 Absorption coefficients of the ceiling materials

	Material	125	250	500	1	2	4	8
		Hz	Hz	Hz	kHz	kHz	kHz	kHz
	Clotex M1	0.12	0.48	0.50	0.79 0.93 0.82 0.48

e-Forum Acusticum, December 7-11, 2020

10.48465/fa.2020.0623

ACKNOWLEGDMENTS

We gratefully acknowledge the support of the Master's Program in Environmental Engineering of the Federal University of Paraná, the Brazilian Government, through the National Council for Scientific and Technological Development -CNPq and CAPES, and the German Government, through the German Academic Exchange Service -DAAD.