Mathilde Vandenberghe-Descamps

Arthur Paté²

Sylvie Chollet

PAIRING A BEER WITH A SOUNDTRACK: IS IT GUIDED BY GEOGRAPHICAL IDENTITY?

Keywords: Beverage, music, pairing, interaction, multisensory perception Highlights

In French gastronomy, food and beverage pairing is a traditional practice set down by pairing principles. Among these, some studies highlighted the principle of "geographical identity": pairing two products related to the same area. While this concept has been explored for foodfood and food-beverage paring, there is less investigation across different senses e.g. auditory and flavory; specifically when flavory stimuli belong to the same food category. Yet it is well known that the auditory environment interacts with food behavior. We can wonder whether the pairing principles identified for food and beverage are relevant for a soundtrack and a beverage and more precisely whether the shared geographical identity of a beverage and a soundtrack drive their association. The aim of the present study is to explore multisensory interaction through the investigation of geographical identity association between a complex beveragea beerand a complex soundtrack (i.e. stimuli with a perceived complexity). The results showed that familiarity and hedonic evaluation of pairs as well as of soundtracks were strongly correlated to harmony evaluation of pairs while familiarity and hedonic evaluation of beers were correlated together. In addition, the results seem to highlight that soundtracks dominate the evaluation of pairs. The present study attempts to demonstrate that pairing multisensory stimuli is complex and the related principles refer to some of the already

INTRODUCTION

Why do we drink wine when eating cheese? In gastronomy, food-beverage or food-food pairing is a traditional practice set down by pairing principles (Anastasia [START_REF] Eschevins | Matching beer with food: pairing principles, underlying mechanisms and a focus on aromatic similarity[END_REF][START_REF] Harrington | Food and Wine Pairing: A Sensory Experience[END_REF][START_REF] Herz | Beer Pairing: The Essential Guide from the Pairing Pros[END_REF][START_REF] Paulsen | Consumer perception of foodbeverage pairings : The influence of unity in variety and balance[END_REF]. According to [START_REF] Paulsen | Consumer perception of foodbeverage pairings : The influence of unity in variety and balance[END_REF] and [START_REF] Harrington | Food and Wine Pairing: A Sensory Experience[END_REF], the most often cited principles refer to balanced intensities of tastes, body, flavor, and aftertaste; aromatic similarity between products and contrasts such as association of fatty food with acidic or tannic wine. In their work, [START_REF] Eschevins | The role of aromatic similarity in food and beverage pairing[END_REF] classified the pairing principles into three categories: perceptual, conceptual and affective pairing principles. According to the authors, perceptual pairing comprises the sensory characteristics of the products, including balance in intensity and enhancement or decrease of sensory properties. The second category, conceptual pairing, involves the extrinsic properties of the products such as the terroir or quality level, the context of consumption and the concept of tradition including geographical identity. This category is commonly encountered in food and wine pairing. Finally, the third category relates to affective pairing and comprises consumer's preference and emotions such as a paring that "deliberately breaks the rules" generating the surprise. In a recent literature review, [START_REF] Galmarini | The role of sensory science in the evaluation of food pairing[END_REF] investigated the topic and scanned the articles that aim at understanding pairing principle in food-food or food-beverage associations. The author confirms that aromatic compound similarityincluded in the perceptual pairing concept defined by [START_REF] Eschevins | The role of aromatic similarity in food and beverage pairing[END_REF] is one of the reasons why a beverage and a food or two foods are matched together; but other reasons were also highlighted. Indeed, according to the author, harmony, balance, sensory similarities, tradition or even geographic origin could be a reason of matching, depending on the food and the beverage. Furthermore, it has been highlighted in this review that principles for pairing a beverage and a food or two foods could be different across the world. Indeed, in a cross-cultural study on food pairing [START_REF] Ahn | Flavor network and the principles of food pairing[END_REF], the authors showed that North American and Western European tend to match foods that share flavor compounds, while East Asian tend to match foods that are different in terms of flavor compounds. In another study, [START_REF] Tallab | Exploring the Food Pairing Hypothesis in Arab Cuisine: A Study in Computational Gastronomy[END_REF] investigated the pairing principles in four Eastern Mediterranean countries: Syria, Lebanon, Palestine and Jordan. The results showed that in those four countries the aroma compound similarity principle is a valid principle. However, this principle is not so clear-cut and may not be working in terms of predicting food or ingredients pairing [START_REF] Spence | Multisensory flavour perception: Blending, mixing, fusion, and pairing within and between the senses[END_REF][START_REF] Spence | Pairing flavours and the temporal order of tasting[END_REF].

While some pairing principles have been largely explored such as the aromatic similarity principle [START_REF] Galmarini | The role of sensory science in the evaluation of food pairing[END_REF], others have, to the best of our knowledge, scarcely been investigated. Among these is the "geographical identity": pairing two products related to the same area [START_REF] Eschevins | Matching beer with food: pairing principles, underlying mechanisms and a focus on aromatic similarity[END_REF]. One may ask whether people associate two products from the same geographical area because they read the labels and make a word association, or whether even in blinded condition people would associate two products coming from the same area. [START_REF] Zellner | Ethnic congruence of music and food affects food selection but not liking[END_REF] investigated this topic, they asked the participants of their study to choose between a Spanish or an Italian dish while listening to either a Spanish or an Italian music. The results showed a significant effect of the music on food choice. In addition, the association of two products from the same area could be related to the evaluation of familiarity: when two products are presented simultaneously, one gets used to the association and gets familiar with those two products together, which could possibly lead to an increase in harmony evaluation over time. A parallel could be made for odor perception: some odors are described as being sweet because an association is made between the smelled odor and the expected taste of the product through a learning process [START_REF] Stevenson | The acquisition of taste properties by odors[END_REF]. Furthermore, as it is well known that familiarity increases the liking [START_REF] Legendre | The impact of consumer familiarity on edible insect food product purchase and expected liking : The role of media trust and purchase activism[END_REF][START_REF] Nacef | Consumers' expectation and liking for cheese: Can familiarity effects resulting from regional differences be highlighted within a country ?[END_REF][START_REF] Stein | Effects of repeated exposure and health-related information on hedonic evaluation and acceptance of a bitter beverage q[END_REF], it could be hypothesized that a pair of products that are familiar when presented together has a greater hedonic rating compared to a pair of two products that are not commonly presented together. From this hypothesis, it is possible to wonder whether this geographical identity principle can be applicable to other objects than food and more generally in cross-modal associations such as taste and sound for example.

For several years now, studies have been conducted to investigate the association between food stimuli and auditory stimuli. Indeed, a few authors investigated the associations between flavor and music (Reinoso [START_REF] Carvalho | Tune That Beer! Listening for the Pitch of Beer[END_REF]Reinoso Carvalho, Wang, van Ee, & Spence, 2016[START_REF] Reinoso-Carvalho | Smooth operator": Music modulates the perceived creaminess, sweetness, and bitterness of chocolate[END_REF][START_REF] Wang | Sounds spicy: Enhancing the evaluation of piquancy by means of a customised crossmodally congruent soundtrack[END_REF]; see [START_REF] Spence | Multisensory flavour perception: Blending, mixing, fusion, and pairing within and between the senses[END_REF] for a review). [START_REF] Crisinel | As bitter as a trombone: Synesthetic correspondences in nonsynesthetes between tastes/flavors and musical notes[END_REF] showed that basic tastes such as sweet, salty or even bitter can be associated with a pitch. The results showed that high-pitched sounds tend to be associated with sweet and sour tastes, while low-pitched sounds tend to be associated with bitter taste. In another study [START_REF] Simner | What sound does that taste? Cross-modal mappings across gustation and audition[END_REF], the authors assessed a cross-modal mapping with taste and sounds. The results show that participants systematically associate basic tastes and the frequency aspects of synthesized speech sounds (the frequency location of the first two formants, which are zones of higher sound level in the speech spectrum, these formants being responsible for the identification of vowels; the vowel discontinuity in time; the spectral balance, i.e., the shape of the frequency spectrum, highlighting either treble or bass frequencies). Moreover, the authors highlight the fact that bitter tastes were associated with sounds having a higher (respectively lower) first formant and a lower (respectively higher) spectral balance than sour (respectively sweet) tastes. However, in this study the participants were given a drop of tastant solution on their tongue before choosing the sound that best matches the taste according to them. This protocol is far from real-life situation as only basic tastes were studied and tasting procedure is intrusive; on the auditory side the stimuli were adhoc synthesized sounds, not recordings of existing music. In a more ecological way, [START_REF] Guetta | When music is salty: The crossmodal associations between sound and taste[END_REF] investigated the cross-modal associations between complex sound and complex taste. Four pieces of music were composed and recorded, representing the four basic tastes according to previously published studies [START_REF] Crisinel | A bittersweet symphony: Systematically modulating the taste of food by changing the sonic properties of the soundtrack playing in the background[END_REF][START_REF] Crisinel | As bitter as a trombone: Synesthetic correspondences in nonsynesthetes between tastes/flavors and musical notes[END_REF], 2011). The pieces of music were presented to the participants, as well as four chocolate ganache: a sweet ganache, a salty ganache, a bitter ganache and a sour ganache. The results showed that the participants associated sound and chocolate ganache that represent the same basic taste. In addition, the authors highlighted the fact that preference ratings for music and chocolate ganache were correlated. Indeed, the participants who preferred the salty sound also preferred the salty chocolate ganache [START_REF] Guetta | When music is salty: The crossmodal associations between sound and taste[END_REF]. Also, some authors investigated the influence of music on food perception and showed that participants evaluated food as sweeter and more intense in taste while listening a music that conveyed positive emotion compared to music that conveyed negative emotion (Reinoso- [START_REF] Reinoso-Carvalho | Not Just Another Pint! The Role of Emotion Induced by Music on the Consumer's Tasting Experience[END_REF][START_REF] Reinoso-Carvalho | Blending Emotions and Cross-Modality in Sonic Seasoning: Towards Greater Applicability in the Design of Multisensory Food Experiences[END_REF][START_REF] Reinoso-Carvalho | A sprinkle of emotions vs a pinch of crossmodality: Towards globally meaningful sonic seasoning strategies for enhanced multisensory tasting experiences[END_REF]. We can notice that most of the studies that investigated the association between sound and flavor were only based on taste association -more precisely on the four basic tastes: sweetness, sourness, saltiness and bitternessor liking (see [START_REF] Spence | Multisensory flavour perception: Blending, mixing, fusion, and pairing within and between the senses[END_REF] for a review), but very few evaluated the link between familiarity and liking on pairs evaluation. In real life, foods, beverages and sonic environments are always very complex; we can wonder whether those studies reflect real-life situations and whether the principles highlighted in the laboratory are still valid in real life. Furthermore, it is well known that the auditory environment interacts with food behavior [START_REF] Kantono | Listening to music can influence hedonic and sensory perceptions of gelati[END_REF][START_REF] North | The effect of background music on the taste of wine[END_REF][START_REF] Carvalho | Music Influences Hedonic and Taste Ratings in Beer[END_REF]; see [START_REF] Dacremont | Context in food behavior and product experience -A review[END_REF] and [START_REF] Spence | Extrinsic Auditory Contributions to Food Perception & Consumer Behaviour : an Interdisciplinary Review Extrinsic Auditory Contributions to Food Perception & Consumer Behaviour : an Interdisciplinary Review[END_REF] for reviews). Accordingly, we propose to investigate pairing principles across different senses, e.g., auditory and gustatory stimuli.

Yet one may ask whether the pairing principles identified for food and beverage or food and food are relevant for a soundtrack and a beverage and more precisely whether the shared geographical identity of a beverage and a soundtrack drive the evaluation of pairs. Therefore, the aim of the present study is to explore multisensory interaction through the investigation of geographical identity association between a complex beverage and a complex soundtrack. More precisely, the harmony of a beer and a soundtrack pairing is investigated through familiarity and hedonic evaluation of pairs, beers and soundtracks. Those three components were shown to be relevant when investigating food-beverage associations [START_REF] Eschevins | The role of aromatic similarity in food and beverage pairing[END_REF]. The present article is divided into two experiments. In the first experiment, the beverages and the soundtracks are characterized using the flash profile method, in order to identify descriptors relevant to characterize both stimuli. The flash profile is a descriptive method combining food choice profiling (participants are free to use their own words) and ranking. It allows to provide a quick access to the relative sensory positioning of a set of products [START_REF] Dairou | A Comparison of 14 Jams Characterized by Conventional Profile and a Quick Original Method[END_REF]. In the second experiment, we investigate the association between the beverages and the soundtracks using three components: harmony, familiarity and hedonic evaluation.

I. EXPERIMENT 1. CHARACTERIZATION OF THE BEVERAGES AND OF THE AUDITORY STIMULI USING FLASH PROFILE

The aim of experiment 1 is to characterize the selected beers and soundtracks. The choice was made to perform a flash profile as participants do not need to be trained to assess the stimuli [START_REF] Valentin | Quick and dirty but still pretty good: A review of new descriptive methods in food science[END_REF].

1) Materials and methods

Participants

Nine participants (5 women and 4 men) aged between 26 and 47 years participated in this study (mean age = 36.4 ± 7.6 year old). The participants are part of the University staff and were recruited through email advertisement. They were invited to participate in two sessions: one for beers and one for soundtracks. The sessions took place at 12:15 PM on two separate days one week apart. The participants were not trained at evaluating neither beer nor music.

Stimuli

Four beers and four soundtracks were used in this experiment. In order to identify the four beers, some pre-tests were conducted. The aim was to identify four beers that are issued from four different parts of the world, typical from their country and different from each other. To do so, a free sorting task and a tasting session to evaluate typicality were conducted with 20 participants, on 18 beers from 12 different countries. The analysis of the typicality test and the free sorting task led us to select the four following beers: O'Hara from Ireland, Bud from the USA, Gazelle from Senegal and Kingfisher from India. Once the four beers were selected, three soundtracks from each corresponding country were selected (i.e. Ireland, the USA, Senegal and India) and a listening session to evaluate their typicality was conducted with 20

French participants that are considered as non-native listeners. The most typical soundtrack from where the beers originate were selected.

Beers

Table 1 presents the four selected beers for the experiment. The beers were stored in a refrigerator at +4°C 24h before the session and were taken out of the refrigerator 30 minutes before each session in order to be served at tasting temperature (6-7°C). The samples were served in 20cl transparent plastic cup in order to allow visual evaluation. About 4cl of each beer was poured in the cups, this quantity assures that the blood-alcohol maximum level cannot be reached.

Table 1 about here

Soundtracks

Table 2 presents the four soundtracks selected for the experiment. The soundtracks correspond either to a movie original soundtrack or a song. Twenty seconds of each soundtrack were extracted and presented to the participants. Participants could listen to soundtracks using headphones Tellememore® connected to a computer.

Table 2 about here

Procedure

Two flash profile sessions took place: one on beers and one on auditory stimuli. Each session consisted of three steps.

During the first step, the participants were asked to taste the beers or listen to the soundtracks as many times as they wanted, and write down every descriptor that could, according to them, discriminate the samples or the soundtracks. The beers and the soundtracks were presented simultaneously: all the beers or all the soundtracks were presented to the participants at the same time, the participants could taste or listen to the stimuli one at a time in a random order.

During the second step, the participants said out loud their descriptors and the experimenter wrote them down on a white board, allowing every participant to have a look at the enunciated descriptors. Then, the participants were asked to focus on their own list and were allowed to add as many descriptors from the other participants as they wanted. Finally, the third step consisted in the evaluation session. The participants were asked to rank the five beers or the four soundtracks on a 10cm linear scale for each descriptor they had on their list.

Ties were allowed and the participants could taste the beers or listen to the soundtracks as many times as they wanted. Again, the beers and the soundtracks were presented simultaneously. Spring water was available and the participants were free to drink water during the sessions. In total, every session lasted approximately 75 minutes. For beer session only, and during the third step of flash profile, one of the four beers was repeated to assess participant's reliability and assess the data: Gazelle from Senegal. This procedure was not setup for soundtracks as the soundtracks were easily recognizable.

Data analysis

For each participant and each descriptor, the data were coded as rank: the lowest intensity corresponding to the rank 1 and the highest intensity to the highest rank. For each participant one data frame was obtained with 5 lines for beers, 4 lines for soundtracks and x columns corresponding to descriptors (as participants could use as many descriptors as they wanted).

Then, two separate Multiple Factor Analyses (MFA) were conducted to analyze the data for beers and soundtracks. Both analyses were performed using XLSTAT® software version 2020-3.1.

2) RESULTS

Beer characterization. Figure 1 presents the first two dimensions of MFA map of the flash profile of beers (75.56 % of the variance). It has to be noted that both repetitions of Gazelle beer are very close on the map confirming that participants' assessment was reliable. The first dimension of the results of the MFA opposes the Bud beer (the USA) which was considered as having an intense sour taste and a low intensity color, to the O'Hara beer (Ireland) which was rated as having a greater color intensity, a greater taste intensity and an intense floral, hoppy, bitter and alcoholic flavor. On the second dimension, the Kingfisher beer (India) was considered as having neither a sour or bitter taste, not sparkling and has not a great amount of foam. Finally, the Gazelle beer (Senegal) is well represented on the third dimension (data not shown) and was rated as being sparkling and having a sweet taste.

Figure 1 about here Soundtrack characterization. Figure 2 presents the first two dimensions of the MFA map of the flash profile of soundtracks (83.71% of variance). Results show that the first dimension opposes the Senegalese soundtrack which was considered as being fast, rhythmic, repetitive, and containing drums, to the American music which was evaluated as being a sentimental soundtrack. The Irish soundtrack is well represented on the second dimension, this soundtrack was considered as being a catchy and dancing soundtrack, cheerful, with high pitch notes, reminding of holidays, but without the presence of drums. Finally, the Indian soundtrack is well represented on the third dimension (data not shown) and was considered as being a rhythmic, complex and oriental soundtrack by the participants.

II. EXPERIMENT 2. PAIRING EVALUATION

The aim of experiment 2 is to investigate whether geographical identity impacts pairing evaluation on cross-modal associations. To do so, the harmony of beers and soundtrack pairing will be investigated throughout familiarity and hedonic evaluation of pairs, beers and soundtracks.

1) Materials and methods

Participants

A hundred and seven participants (41 women and 66 men) aged between 18 to 27 years participated in this study (mean age = 20.44 ± 1.9 year old). Participants were students from one university based in Lille (France). As it is well known that age have an influence on food and music perception [START_REF] Kremer | Food perception with age and its relationship to pleasantness[END_REF][START_REF] Stothart | Auditory perception in the aging brain: the role of inhibition and facilitation in early processing[END_REF], the choice was made to recruit students, a homogeneous group of beer drinkers and music listeners. They were recruited throughout recruitment posters and social media's advertisement. The trials were carried out from 11AM to 5PM, participants were free to come to the laboratory anytime during this time slot.

Stimuli

Beers

The four beers of Experiment 1 were served in Experiment 2, i.e. O'Hara (Irish beer), Bud (American beer), Gazelle (Senegalese beer) and Kingfisher (Indian beer) (see Stimuli of experiment 1 and table 1). Beers were stored in a refrigerator at +4°C 24h before the session then were taken out of the refrigerator 30 minutes before each session in order to be served at tasting temperature (6-7°C). The samples were served in a 20cl transparent plastic cup in order to allow visual evaluation. About 2cl of each beer was poured in the cups, this quantity assures that the blood-alcohol maximum level cannot be reached according to French legislation.

Soundtracks

The four soundtracks of Experiment 1 were used for Experiment 2 (see Stimuli of Experiment 1 and table 2). Participants could listen to musical extracts using headphones (Tellememore®) connected to a computer.

Procedure

The pairing evaluation was divided into three steps: 1) the evaluation of beer-soundtrack associations; 2a) the evaluation of beers; 2b) the evaluation of soundtracks; 3) the sociodemographic questionnaire. For the first step, the pairs were evaluated according to harmony, familiarity and hedonic components. For the second step, beers and soundtracks were evaluated on the familiarity and hedonic components.

Evaluation of the association beer-soundtrack. Participants performed the harmony, familiarity and hedonic evaluation of each pair using a 10-point scale (from not at all to very much). For those three components, the pair was evaluated as an entity in itself. Beers and soundtracks were presented as pairs to the participants, following a William Latin square design. Each beer was presented with each soundtrack; therefore each participant evaluated 16 pairs. Participants could listen to the soundtrack and taste the beers as many times as they wanted. They were asked to rinse their mouth between each pair's evaluation using bottled spring water.

Then, participants were asked to evaluate the beers and soundtracks separately. Half of the participants started with beer evaluation, the other half with soundtrack evaluation.

Evaluation of beers. The four beers were presented one at a time to the participants following a William Latin square design. Participants performed the familiarity and hedonic evaluation of each beer using a 10-point scale (from not at all to very much). They were asked to rinse their mouth between each beer evaluation using bottled spring water.

Evaluation of soundtracks. The four soundtracks were presented one at a time to the participants following a William Latin square design. Participants performed familiarity and hedonic evaluation of soundtracks using a 10-point scale (from not at all to very much), they could listen to the soundtrack as many times as they wanted.

Socio-demographic questionnaire. At the end of the session, participants were invited to answer socio-demographic questions as well as questions regarding beer consumption frequency, musical practice and music listening frequency. Among the socio-demographic questions, the number of years of musical experience as well as instrument practice was asked to the participants.

The sessions were conducted in a sensory room designed according to ISO guidelines (ISO International Organization for Standardization, 2007). Tasting was conducted in individual sensory booths under white light at a room temperature of 20°C ± 0.5. The beers and soundtracks were coded with different three-digit numbers.

Data analysis

χ² tests were performed to analyze the study population. To analyze cross-modal association, an analysis of variance (ANOVA) was carried out considering the beer and the soundtrack as factors and the harmony, familiarity and hedonic scores as dependent variable. When a significant effect was found, a Newman Keuls pair comparison test was performed with a αlevel at 5%. For familiarity and hedonic evaluation of beers and soundtracks, an ANOVA was carried out with beer or soundtrack as factor and familiarity and liking scores as dependent variables. When a significant effect was found, a Newman Keuls pair comparison test was performed with a α-level at 5%. Finally, an Principal Component Analysis (PCA) was performed on the 16 associations and on the seven variables issued from the results: harmony, familiarity and hedonic evaluation of beer-soundtrack pairs, familiarity and hedonic evaluation of beers, as well as familiarity and hedonic evaluation of soundtracks.

Statistical analyses were performed using XLSTAT® software version 2020-3.1.

2) RESULTS

Study population

Table 3 shows the characteristics of the study population. No significant differences were observed regarding age distribution between men and women (χ²=3.6; ns), as well as travels abroad (χ²=0.006, ns), number of years of music training (χ²=2.6, ns), practice of an instrument (χ²=2.2, ns) and frequency of listening to music (χ²=6.9, ns). However, a significant difference was observed regarding beer frequency consumption: women consume beer less often than men as they are more likely to consume beer once a month or several times a month while men are more likely to consume beer several times a week (χ²=18.9, p=0.002). The study population may therefore be considered as being balanced.

Table 3 about here

Beer-soundtrack pairing

The two-way ANOVA shows a significant effect of soundtrack but no effect of beers on harmony, familiarity and hedonic evaluation (p<0.001 for the three variables regarding soundtrack). Indeed, regardless of the beers, the average scores of harmony, familiarity and liking are greater for pairs containing Irish or American soundtrack than for pairs containing Senegalese or Indian soundtrack (Table 4).

Table 4 about here Furthermore, we can see a tendency for the interaction between beers and soundtracks for harmony evaluation: the two pairs considered as most harmonious according to the participants were the pairs Bud-USA (M = 6.6 ± 2.5) and Kingfisher-IRELAND (M = 6.4 ± 2.6). It has to be noted that the O'hara-IRELAND arrives in third position in terms of harmony evaluation (M =6.1 ± 2.8). On the contrary, the two pairs that were considered as less harmonious according to the participants were the pairs Gazelle-SENEGAL (M = 4.8 ± 2.6) and the pair O'Hara-SENEGAL (M =4.8 ± 3.0) pair. In general, pairs containing either the Irish of the American soundtrack are considered as more harmonious compared to the other pairs (Table 5).

Concerning familiarity and hedonic evaluation, no interaction has been highlighted. The scores of familiarity show that the pairs containing the Irish of the American soundtracks are more familiar than the pairs containing either the Senegalese of the Indian soundtrack, whatever the beer. Regarding hedonic scores, as for the familiarity evaluation, pairs containing either the Irish or the American soundtracks are more liked whatever the beer, except for the pair O'Hara -USA. Again, the pairs containing either the Senegalese of the Indian soundtrack are less liked.

No difference was observed depending on socio-demographic data: The evaluation does not differ depending on gender, beer frequency consumption, music frequency exposition or years of music experience.

Table 5 about here

Figure 3 presents the first two dimensions of the PCA maps explaining 91.78% of the variance. Results show that familiarity and hedonic evaluation of pairs as well as familiarity and hedonic evaluation of soundtrack are strongly correlated to harmony evaluation of pairs (R=0.86, p<0.001; R=0.96, p<0.001; R=0.78, p=0.001 and R=0.74, p<0.001 respectively).

Familiarity and hedonic evaluation of beers are correlated together (R=0.90, p<0.001).

Regarding beer-soundtrack pairs (Figure 3b), the first dimension opposes pairs containing either the Irish or the American soundtrack, which are more familiar and more liked, compared to the pairs containing either the Senegalese or the Indian soundtrack, which are less familiar and less liked. The second dimension opposes pairs containing the beers O'Hara or Bud which are more familiar and more liked, compared to the pairs containing either Kingfisher or Gazelle which are less familiar and less liked.

Figures 3a and 3b about here

Beer evaluation

Figures 4a and4b show the results of the one-way ANOVA on beers for familiarity and hedonic evaluations respectively. A significant effect was observed on both variables (p<0.0001 and p=0.03 respectively). For familiarity evaluation, O'Hara and Bud are significantly more familiar than Gazelle and Kingfisher. Regarding the hedonic evaluation, O'Hara is the most preferred beer while Kingfisher is the less preferred beer.

Soundtrack evaluation

Figures 4c and4d show the results of the one-way ANOVA on soundtrack evaluation for familiarity and hedonic evaluations respectively. A significant effect was observed on both variables (p<0.0001 for both variables). Similar results are observed for both variables: the Irish soundtrack is the most familiar and most liked while Senegalese and Indian soundtracks are the less familiar and less liked. Besides, whether it is for familiarity or hedonic evaluation, Irish and American soundtracks were rated as significantly different while Senegalese and Indian soundtracks were not rated as significantly different.

Figures 4a,4b, 4c and 4d about here

III. DISCUSSION

The aim of the present study was to explore multisensory interaction through the investigation of geographical identity association between a complex beverage and a complex soundtrack.

More precisely, the harmony of beverage and soundtrack pairing was investigated throughout familiarity and hedonic evaluations of pairs, beverages and soundtracks.

Overall, the results showed that familiarity and hedonic evaluation of pairs as well as of soundtracks were strongly correlated to harmony evaluation of pairs while familiarity and hedonic evaluation of beers were correlated together. In addition, results showed that whatever the beer, pairs containing either the Irish or the American soundtrack were considered as being more harmonious, more familiar and more liked compared to the pairs containing the Senegalese or the Indian soundtrack. As Reinoso [START_REF] Carvalho | Tune That Beer! Listening for the Pitch of Beer[END_REF], our results highlight link between auditory and olfactory and flavory stimuli. These authors explain this result based on physical properties: Most salient taste attribute, degree of alcohol and range of pitch. In the present study, we suggest a complementary explanation: The link between auditory and olfactory and gustatory stimuli could also be due to the concept of harmony and familiarity of both beers and soundtracks.

Several hypotheses could explain the results of the present study. First, our results could be explained by the sensory dominance of judgment. Some studies highlighted that when two stimuli are presented simultaneouslyone visual and one auditorythere is a prepotency of the visual over the auditory stimulus [START_REF] Colavita | Human sensory dominance[END_REF]. One can wonder whether this concept is applicable for auditory and flavory stimuli. Also, as the soundtracks are clearly different and recognizable whereas the beers present less differences and are probably not recognizable when blinded, people may simply ignore the minor differences in beer and only focus on music to evaluate pairs. Consequently, it is possible that in absence of bottom-up differentiation of beers based on flavor, participants based their judgements on top-down information coming from music identification.

Second, it could be hypothesized that participants evaluated the pairs as more harmonious when the two stimuli present similar sensory characteristics, i.e. when both stimuli have strong sensory characteristics or on the contrary when they seem to have a less pronounced identity. According to [START_REF] Eschevins | The role of aromatic similarity in food and beverage pairing[END_REF], this hypothesis refers to one of the three enunciated pairing principles: the perceptual principle. Therefore, two stimuli with similar sensory characteristics could go well together and be perceived as harmonious, as it was observed for food-food associations where shared aromatic compounds or sensory characteristics lead to a preferred association [START_REF] Galmarini | The role of sensory science in the evaluation of food pairing[END_REF]. This pairing principle could therefore be considered as universal whatever the involved senses.

Third, it could be hypothesized that familiarity and hedonic evaluation have an impact on the evaluation of pairs. Indeed, the pairs that were rated as the most harmonious seem to contain either a beer or a soundtrack that was rated as the most familiar and the most liked by the participants. In addition, it has to be noted that the pairs that were rated as more harmonious compared to the others contained both a beer that was familiar and liked and a soundtrack that was familiar and liked. This leads us to believe that two stimuli that are either familiar or liked go well together, and the pair containing those two stimuli is harmonious. It is also possible (and might be tested in further studies) that the monomodal familiarity and/or hedonic evaluation of beers and soundtracks predict well the multisensory harmony evaluation of the beer/soundtrack pairs. This hypothesis goes in line with the fact that familiarity increases the liking: two products presented together have a greater hedonic rating when they are familiar compared to two products that are not commonly presented together [START_REF] Legendre | The impact of consumer familiarity on edible insect food product purchase and expected liking : The role of media trust and purchase activism[END_REF][START_REF] Nacef | Consumers' expectation and liking for cheese: Can familiarity effects resulting from regional differences be highlighted within a country ?[END_REF][START_REF] Stein | Effects of repeated exposure and health-related information on hedonic evaluation and acceptance of a bitter beverage q[END_REF]. Also, some authors demonstrated that familiarity and hedonic ratings are positively correlated in various domains such as vision [START_REF] Zajonc | Attitudinal effects of mere exposure[END_REF], odors [START_REF] Chrea | Semantic, typicality and odor representation: A cross-cultural study[END_REF][START_REF] Engen | chapter 8 -Odor hedonics[END_REF] or food [START_REF] Nicklaus | A prospective study of food preferences in childhood[END_REF][START_REF] Sulmont | Impact de la mémoire des odeurs sur la réponse hédonique au cours d'une exposition répétée[END_REF]. Finally, the impact of hedonic evaluation seems to have its importance for both beers and soundtracks. It could be hypothesized that the "flavor-flavor learning" concept may be relevant for beer and soundtrack: when a new flavor is presented in a repetitive manner and associated with a liked flavor, the new flavor is well liked. On the contrary, when a new flavor is associated with an unliked flavor, it becomes unliked (D. A. [START_REF] Zellner | Conditioned enhancement of human's liking for flavor by pairing with sweetness[END_REF]. Here, presenting whether a new beer or a new soundtrack with a soundtrack or a beer that are already liked would increase the hedonic rating of the new beer or the new soundtrack.

In order to confirm those hypotheses, several leads may be considered. First of all, only four beers and four soundtracks were presented to the participants, even though many others could have been studied. It is difficult to fully represent the geographical identity of one country in a single beer or a single music, it would be interesting to present a set of various stimuli issued from one country to better investigate the effect of geographical area on pairing. However, as the tasted products are alcoholic products, it was important not to serve too much beer in order to make sure that the legal alcoholic level was not reached by any of the participants. In addition, it is necessary to pour enough beer for participants to answer to all the questions.

Therefore, the number of served beers was restrictive and the authors of the present study found that four beers was a reasonable number of products as 16 samples were served in total: the 4 beers x the 4 soundtracks. Furthermore, beer is a very complex matrix containing more than 3000 different compounds [START_REF] Anderson | A review of the analytical methods used for beer ingredient and finished product analysis and quality control[END_REF]. Indeed, the more beers are presented to the participants, the more difficult the task is to assess the beers.

Serving more than four beers to the participants may increase cognitive load and tiredness during the test [START_REF] Sharif | Sensory Evaluation and Consumer Acceptability[END_REF]. Therefore, it is strategic not to serve too many samples of beers to the participants.

Second, regarding geographical associations, the choice was made to perform the association assessment task asking only French students, the students were asked to assess four beers that are not originated from France. This way, we made sure that all the participants had the same understanding of the questions and the same background culturally speaking. However, it would be interesting to investigate whether American, Indian, Irish or Senegalese students assess the beer-soundtrack associations the same way or not, and whether French students assess the French beers differently as they were more exposed to French beers and therefore are more familiar with them as compared to the other beers. An idea would be to add a fifth beer in the study: a typical French beer. That way, we could investigate the influence of cultural background on harmony, familiarity and hedonic assessment of beer-soundtrack pairs. In addition, it would be interesting to assess cultural knowledge of the participants to evaluate whether the participants are familiar with the culture of the countries where the beers and soundtracks are originated. Knowing whether the participants have already been to these countries, tasted the beers and are familiar with the soundtracks of those specific countries would give clues to understand the impact of familiarity on pairs evaluation.

Third, the results showed that while the four soundtracks are all different in terms of characteristics, the Irish beer is very different from the other beers (see figure 1b, axis F1).

That is to say, the soundtracks are well divided in terms of difference compared to the beers. Indeed, the Irish beer is the one having the most intense taste in general and the most pronounced characteristics according to the participants of the flash profiling task, while the other beers had a less intense taste. Also, the Irish beer was the only one having an amber color, the three other beers were blond beers. It would have been interesting to select four beers with four distinct characteristics as it was the case for the soundtracks: a very sweet beer, a very hoppy beer, a very sour beer and a very bitter beer for example. That way, the four beers would have had four distinct profiles and be closer to the four soundtracks who were very distinguishable between each other. Additionally, it is possible that our choice of soundtracks spans a broader range of diversity than our choice of beers do. In other words, we might have chosen soundtracks that are more different from each other than beers are from each other. Having exposed the participants to auditory stimuli that were more diverse than gustatory stimuli might explain why the beer/soundtrack harmony seems to be driven by soundtrack familiarity and liking (see above and figure 3a, axis F1).

Finally, it has to be noted that the participants evaluated the associations in a standardized laboratory, using headphones to listen to the soundtracks. It is now well known that context has a significant impact on food perception and liking. Many studies have indeed investigated the topic, comparing various contexts with several degree of immersioni.e. sensory laboratory, virtual reality, immersive room or in-home tests [START_REF] Bangcuyo | The use of immersive technologies to improve consumer testing: The role of ecological validity, context and engagement in evaluating coffee[END_REF][START_REF] Boutrolle | Comparing central location test and home use test results: Application of a new criterion[END_REF][START_REF] Boutrolle | Central location test vs. home use test: Contrasting results depending on product type[END_REF][START_REF] De Wijk | Food perception and emotion measured over time in-lab and inhome[END_REF][START_REF] Hannum | Does environment matter? Assessments of wine in traditional booths compared to an immersive and actual wine bar[END_REF][START_REF] Hathaway | The impact of multiple immersion levels on data quality and panelist engagement for the evaluation of cookies under a preparation-based scenario[END_REF][START_REF] Hehn | 23 -Inducing context with immersive technologies in sensory consumer testing[END_REF][START_REF] Lichters | Segmenting consumers based on sensory acceptance tests in sensory labs, immersive environments, and natural consumption settings[END_REF][START_REF] Liu | Using immersive technologies to explore the effects of congruent and incongruent contextual cues on context recall, product evaluation time, and preference and liking during consumer hedonic testing[END_REF][START_REF] Schouteten | Influence of organic labels on consumer's flavor perception and emotional profiling: Comparison between a central location test and home-use-test[END_REF][START_REF] Stelick | Thinking outside the booth-the eating environment, context and ecological validity in sensory and consumer research[END_REF]. Whereas the results of the studies do not always lead towards the same conclusions, all results show an increase in participant's engagement. Thus, when one drinks a beer while listening to music, it is commonly in a pub or at home with family and friends. In addition, when drinking a beer in a pub, the customers do not need to wear headphones as the music is diffused using loudspeakers. Therefore, this laboratory situation is not the most ecological situation, when talking about beer consumption and music listening (Galiñanes Plaza, [START_REF] Galiñanes Plaza | The pursuit of ecological validity through contextual methodologies[END_REF]. It would be interesting to perform such a task in a more ecological environment, such as an immersive room or in a real pub for example. Indeed, in a recent study investigating the influence of environment on beer consumption [START_REF] Delarue | Taking control of product testing context thanks to a multi-sensory immersive room . A case study on alcohol-free beer[END_REF], the authors highlighted the fact that the immersive situation could reduce the effect of time assessment. Indeed, their results showed that the difference between morning and afternoon sessions was significant in the non-immersive condition but not significant in the immersive condition. Therefore, it could help the participants to immerse themselves into a more realistic situation. Only relevant descriptors are presented in figure 1a: either descriptors that were cited at least by three different participants and whose contribution is greater than the mean contribution of all descriptors or having a cosinus² > 0.5. Only relevant descriptors are presented in figure 2a: either descriptors that were cited at least by three different participants and whose contribution is greater than the mean contribution of all descriptors or having a cosinus² > 0.5.

Holidays

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Figure 1 .

 1 Figure1. Multiple Factor Analysis (MFA) plots of flash profile data on beers for dimensions 1 and 2 (1a: descriptors; 1b: Beer map).

Figure 2 .

 2 Figure 2. Multiple Factor Analysis (MFA) plots of flash profile data on soundtracks for dimensions 1 and 2 (2a: descriptors; 2b: soundtracks map).

Figure 3 .

 3 Figure 3. Principal Component Analysis (PCA) for dimensions 1 and 2: 3a evaluation variables; 3b beer-soundtrack pairs.

Table 5 .

 5 Means and standard deviations for beer-soundtrack pairs on harmony, familiarity and hedonic evaluation For each variable, means in the same column with different letters are significantly different (p<0.05) according to the Newman Keuls test.

	Beer-music	Harmony of pairs	Familiarity of pairs	Liking of pairs
	Bud -USA	6.6 ± 2.5	a	5.5 ± 2.8	a	6.7 ± 2.7	a
	Kingfisher -IRELAND	6.4 ± 2.6	ab	5.3 ± 3.1	a	6.4 ± 2.8	ab
	O'Hara -IRELAND	6.1 ± 2.8	abc	5.3 ± 3.0	a	6.2 ± 3.0	abc
	Gazelle -USA	6.0 ± 2.6	abcd	5.1 ± 3.1	a	6.2 ± 2.7	abc
	Gazelle -IRELAND	5.9 ± 2.8	abcde	5.1 ± 3.0	a	6.0 ± 3.0	abcd
	Bud -IRELAND	5.9 ± 2.7	abcde	5.2 ± 2.8	a	6.1 ± 2.8	abcd
	O'Hara -INDIA	5.8 ± 2.9	abcde	3.2 ± 2.5	b	5.2 ± 3.1	cde
	Kingfisher -USA	5.6 ± 2.7	abcde	5.0 ± 3.0	a	5.6 ± 2.9	abcde
	O'Hara -USA	5.5 ± 3.1	bcde	4.7 ± 3.0	a	5.4 ± 3.4	bcde
	Kingfisher -INDIA	5.3 ± 2.7	bcde	3.1 ± 2.6	b	5.1 ± 2.6	cde
	Bud -INDIA	5.3 ± 2.6	bcde	3.5 ± 2.7	b	5.4 ± 2.6	bcde
	Bud -SENEGAL	5.2 ± 2.4	cde	3.4 ± 2.7	b	5.2 ± 2.5	cde
	Kingfisher -SENEGAL	5.1 ± 2.7	cde	3.4 ± 2.7	b	4.9 ± 2.7	de
	Gazelle -INDIA	5.0 ± 2.8	cde	3.1 ± 2.7	b	4.8 ± 3.0	e
	Gazelle -SENEGAL	4.8 ± 2.6	de	3.1 ± 2.6	b	4.8 ± 2.8	e
	O'Hara -SENEGAL	4.8 ± 3.0	e	2.9 ± 2.6	b	4.5 ± 3.1	e

Acknowledgements

The authors thank Salamata Baldé for the work she did on the tasting sessions, and all the participants of the present study.

CONCLUSION

The present study aimed at investigating multisensory interaction through the evaluation of beer-soundtrack associations. Harmony, familiarity and liking of pairs, beers and soundtracks were assessed in order to investigate whether geographical identity is a relevant pairing principle for beer-soundtrack associations. As a result, the present study attempts to demonstrate that pairing multisensory stimuli is complex and refers to some of the already highlighted pairing principles for food-food pairing: geographical identity but also perceptual principles. In order to deeply investigate the influence of geographical identity on associations assessment, it could be interesting to study products that are traditionally associated together, for example wine with cheese, and see if, blinded, the participants still consider this association as harmonious, liked and familiar.

Ethical Statements

The authors declare that they do not have any conflicts of interest.