Professor CHARLES SPENCE of Oxford University’s Crossmodal Research Laboratory explains the impact sound has on your perception of flavor.
In fact, everything from the sound of the coffee machine through to the background noise/music in your favorite coffee shop has been shown to influence our sensory expectations, not to mention our coffee drinking behavior.
One of the most obvious sounds associated with specialty coffee is the sound of the machine itself. A few years ago, here in Oxford University, we recorded the sound of ten professional coffee machines as they dispensed a standard drink. We then had people rate their expectations of the taste of the coffee based on nothing more than the sound of the machine as it was grinding, dripping, steaming, ejecting, etc. Intriguingly, there was little relation between the sound of the machine and the quality/prestige of the brand, with one of the most expensive commercial coffee machines sounding like nothing so much as a reversing truck! Needless to say, that sound didn’t set the best taste expectations.
But do these sounds, which mostly pass unnoticed, really make a difference to how the coffee tastes? That was the question that Klemens Knöferle, a post-doctoral researcher in my lab, set out to answer. Two hundred or so people were invited into the Crossmodal Research Laboratory to drink a Nespresso and rate its taste. Everyone got to taste exactly the same coffee; all that was varied was the noise given off by the machine that made it. In particular, the sounds were made sharper/harsher (boosting the high-frequency noise components) for half of the participants. The results showed that this sound manipulation led to the coffee being rated as tasting significantly lower in quality than if the machine sounds had the regular sound instead. Next comes the sound of the milk being frothed. Here, too, sound matters, though more for the barista whose trained ear judges the temperature of the milk by the squealing sound of the hot air escaping from the jug.
In terms of the drinking experience itself, the first thing to consider is the detrimental effect of all that background noise, more than 80–100 decibels in many bars and restaurants these days. So loud, in fact, that not only may it be damaging the hearing of those employees exposed to such noise levels for long periods of time, but the evidence suggests that it may actually suppress our ability to taste sweet and salt, as well as impairing our ability to discriminate between different aromas. And while noise-absorbing materials and technologies do exist, their expense has thus far limited their commercial uptake in dampening the noise. Of course, all that stressed wood (the stripped-back Nordic look), not to mention the hard seating that one finds in so many coffee shops these days doesn’t help here either, tending to reflect, rather than to absorb, the noise.
However, assuming that the background noise isn’t too loud, how might any music playing in the background be impacting your coffee drinking behavior? Once again, the evidence suggests more than you might think. So, for instance, louder and faster music has been shown to increase the speed/amount that customers eat and drink in restaurants (sometimes by as much as 27 percent). What is more, if the intriguing body of research from the world of wine is anything to go by, your choice of Colombian or Kenyan blend probably has as much to do with whether it is the music of Shakira or East Africa that happens to be playing innocuously in the background. None of us believe that the music can have such a profound influence on our choices. However, the growing body of evidence from the emerging field of sensory marketing clearly demonstrates that it can. And beyond the country associated with the music in the mind of the taster, its style also impacts our judgments. So, for instance, a number of real-world studies have shown that playing classical music (perhaps Bach’s Coffee Cantata), when compared to Top-40 tracks, say, primes notions of quality/class and that means that shoppers/diners spend more on their food and drink purchases. What is more, they tend to rate whatever they are eating and drinking as being of higher quality too!
However, beyond these generic music effects, there is also an emerging body of research on “sonic seasoning.” This is the name given to the surprising impact that certain pieces of music/soundscapes have been shown to have on the tasting experience. Strange though it may sound (if you’ll excuse the pun), playing more tinkling high-pitched music – think the tinkling piano/wind chimes that one finds in Mike Oldfield’s Tubular Bells, or Saint-Saëns Carnival of the Animals – has been shown to bring out the sweet notes in bittersweet foods such as dark chocolate, cinder toffee, and (slightly sweetened) black coffee. By contrast, the playing of low-pitched brassy music makes the bitter notes suddenly become a lot more pronounced. Sound designers, composers, etc. have now developed tracks to accentuate the acidity, too (both on the palate and on the nose). We have been working with Belgian chocolatiers, like Dominique Persoone of The Chocolate Line, to develop creamy music than can bring out the smoothness in the chocolate. Would the same music also bring out the smoothness of your cup of coffee? Only further research will tell. The key point to note for now, though, is that you cannot use music to turn water into wine. The taste, aroma, flavor, and/or mouthfeel characteristic has to be there in the drink to begin with. What you can do, though, is to use sonic seasoning to help draw a taster’s attention to something in a complex tasting experience that they might not otherwise notice and, by so doing, make it more salient in their tasting experience.
And while it might sound bizarre, many food and beverage companies are becoming increasingly interested in the field of sonic seasoning, often working with composer sound designers/sonic branding agencies in order to try and create music tracks/soundscapes that perfectly match a very specific time-evolving tasting experience. Indeed, the world of coffee seems ripe for this kind of sonic design, given the close links between coffee and music that are already stressed by a number of producers (think here of how the likes of Nespresso makes reference to music, and musical instruments/notes/notation in so much of its advertising – just take its Symphony Assortment). And, in an early precursor to this approach, a decade ago I worked with Starbucks here in the UK to develop a track that coffee drinkers could download so as to enhance the taste of the new Starbucks Via coffee designed for home consumption.
So, next time you order a coffee and find that the taste is not quite as you remember it, perhaps you should not blame the barista, but rather ask yourself whether or not the background music/noise might not be having more of an influence over your tasting experience than you ever thought possible. Looking to the future, I believe that it is only by recognizing the key role played by acoustic/sonic design in setting flavor expectations/modifying flavor perception, be it in the world of coffee or anywhere else for that matter, that we can really hope to optimize our multisensory tasting experiences, and those of the consumers we serve. Never forget, sound really is the forgotten flavor sense.
CHARLES SPENCE is a Professor of Experimental Psychology and the head of the Crossmodal Research Laboratory at Oxford University.
 Knoferle, K. M. (2012). Using customer insights to improve product sound design. Marketing Review St. Gallen, 29(2), 47–53.
 Belluz, J. (2018). Why restaurants became so loud — and how to fight back “I can’t hear you.” Vox Media, April 25th Farber, G., & Wang, L. M. (2017). Analyses of crowd-sourced sound levels, logged from more than 2,250 restaurants and bars in New York City. The Journal of the Acoustical Society of America, 142, 2,593.
 Spence, C. (2014). Noise and its impact on the perception of food and drink. Flavour, 3:9.
 Shelton, A. (1990). A theatre for eating, looking and thinking: The restaurant as symbolic space. Sociological Spectrum, 10, 507–526.
 Reinoso Carvalho, F., Wang, Q. (J.), van Ee, R., Persoone, D., & Spence, C. (2017). “Smooth operator”: Music modulates the perceived creaminess, sweetness, and bitterness of chocolate. Appetite, 108, 383–390.
 Spence, C. (2017). Sonic seasoning. In L. Minsky & C. Fahey (Eds.), Audio branding: Using sound to build your brand (pp. 52–58). London, UK: Kogan Page.
 Spence, C. (2017). Gastrophysics: The new science of eating. London, UK: Viking Penguin.
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