“Food and drink are among life’s most multisensory experiences,” Spence pointed out, so it’s perhaps hardly surprising that it occurred to him that the parchment skin illusion might work in the mouth, using food rather than clothing. He recruited 200 volunteers willing to eat Pringles for science, and played them modified crunching sounds through headphones, some louder and some more muffled, as they ate. And he found that he could make a 15 percent difference in people’s perception of a stale chip’s freshness by playing them a louder crunch when they bit into it.
“The party version” of this trick, according to Spence, was developed by colleagues in the Netherlands and Japan. Volunteers were asked to crunch on chips in time with a metronome, while researchers played crunching sounds back, in perfect synchrony, through their headphones. All was well until the researchers replaced the crunching with the sound of breaking glass—and “people’s jaws just freeze up.”….
Give it a listen.