The following is an article from the Annals of Improbable Research.
The sounds of crisp chips (crisps) and stale chips (crisps)
by Marc Abrahams, Improbable Research staff
Crispness is associated with crunchiness, but your ears make a difference. That’s the take-away-and-chew-on-it message of an Oxford University study1 called “The Role of Auditory Cues in Modulating the Perceived Crispness and Staleness of Potato Chips.”
The authors, experimental psychologists Massimiliano Zampini and Charles Spence, wax distantly poetical:
We investigated whether the perception of the crispness and staleness of potato chips can be affected by modifying the sounds produced during the biting action. Participants in our study bit into potato chips with their front teeth while rating either their crispness or freshness using a computer-based visual analog scale.
They recruited volunteers who were willing to chew, in a highly regulated way, on Pringles potato crisps. Pringles themselves are, as enthusiasts well know, highly regulated. Each potato chip (or crisp, as it is known in the U.K.) is of nearly identical shape, size and texture, having been carefully manufactured from reconstituted potato goo.
The volunteers were unaware of the true nature of their encounter -- that they would be hearing adulterated crunch sounds. But whatever risks this entailed were small. The experiment, Zampini and Spence take pains to say in their report, “was performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki. Participants were paid £5 for taking part in the study.”
Each volunteer sat in a soundproofed experimental booth, wearing headphones, facing a microphone, and operating a pair of foot pedals.
The headphones delivered Pringles crunch sounds that, though born in the chewer’s mouth, had been captured by the microphone and electronically cooked. At times, the crunch sounds were delivered to the headphones with exacting, lifelike fidelity. At other times, the sounds were magnified. At still other times, only the high frequencies of the crunch were intensified.
The foot pedals were the means by which a volunteer could register his or her judgments as to (a) the crispness and (b) the freshness of a particular crisp.
Each crisp’s crispness was judged from a single, headphone-enhanced bite delivered with the front teeth. Zampini and Spence adopted this approach for two reasons. It maximized the uniformity of the participant’s contact with each crisp. And previous research, by others, showed that the sound of the first bite is what counts most for judging crispness.