All of our senses, it seems, pitch in to help us enjoy a meal — that is, all of them except for one. We taste our food, obviously, but what we perceive as flavor is also odor and texture, making each bite an experience of touch and smell. And anyone who’s ever watched a Top Chef judge berate a contestant for a sloppily plated dish (or, um, been on Instagram) knows that we eat with our eyes, too. And then there are your ears, left out and useless, just sitting dumbly on your head as you chew. Hearing doesn’t really have a place at this party.
At least, not one that we’re aware of. But as this video from PBS’s BrainCraft explains, our sense of hearing actually plays a small but essential role in how we experience our food — it’s one of the weirder, more subtle examples of a phenomenon called cross-modal association, where multiple senses work together to alter the way we perceive our surroundings.
While sound can’t create a flavor that doesn’t exist, it can enhance certain elements already present within a given food. “Researchers have found that people can reliably match certain tastes with specific tones,” said BrainCraft host, Vanessa Hill: High-pitched tones bring out sweet and sour notes, while lower pitches do the same for umami and bitter. In one 2012 experiment, volunteers munching on toffee described it as sweeter when researchers played high-pitched background noise, and more bitter when they were listening to lower sounds.
Plenty of research has explored how this hearing-taste link plays out in specific foods. A 2005 study, for example, found that people perceived stale potato chips as fresher if researchers played louder crunching noises as they ate, perhaps because they connected the noise to what was happening inside their mouths. And there’s a reason that tomato juice, typically the neglected stepchild of the juice family, is so much more popular on flights: Loud noise makes us more sensitive to umami flavors. (The inside of an airplane cabin can get up to 105 decibels; for comparison, a typical Manhattan street is around 70 decibels, and a subway platform reaches around 80 as a train arrives). Our ears are even finely tuned enough to hear temperature: If you pour steaming-hot tea into a mug, it’ll sound slightly different than if you do the same thing with cold water, a difference that could in turn influence your perception of whatever you’re about to take a sip of.
Knowledge of food’s auditory properties has now spilled outside the lab and into everyday dining experiences, too. Some food critics, for instance, now make sure to note a restaurant’s noise level, which research has shown can make a difference in how much we like what we’re eating, and some establishments have even tried to harness specific sounds for their benefit. The U.K. restaurant The Fat Duck offers a dish called Sound of the Sea: a seafood platter served with an iPod, loaded up with recordings of the ocean to play during the meal. And chefs at Chili’s, Hill noted, “speak of the fajita effect, where one person ordering a sizzling, crackling skillet of fajita meat leads to an influx of fajita orders from other diners.”
Researchers still aren’t entirely sure why a given sound will correspond to certain tastes, but as Nicola Twilley noted in The New Yorker last year, part of it may have to do with language, in ways both innate and learned: “Some correspondences may be universal. The connection between high-pitched sounds and sweet tastes is likely based on their shared oral configuration: an infant’s tongue moves outward and upward in response to sweet foods, as does an adult’s when he is singing falsetto,” she wrote. “In other cases, the relationship might be culturally dependent, based on similar words being used across sensory modes — edges can look and feel sharp, but Cheddar can be described that way, too.”
In other words, the terms we use — sharp edges, sharp cheese — can unwittingly reveal a strange truth about the way we navigate the world: It’s rare that we experience one sense on its own, isolated from all others. More often, they’re collaborating in ways we don’t fully comprehend or even realize, blending together like individual flavors to create a new, distinct whole.