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.
The results? As the report puts it:
The potato chips were perceived as being both crisper and fresher when either the overall sound level was increased, or when just the high frequency sounds (in the range of 2 kilohertz-20 kilohertz) were selectively amplified.
Zampini and Spence say this gives new insight on an old research finding. In 1958, in the Journal of Applied Psychology, G.L. Brown “reported that bread was judged as being fresher when wrapped in cellophane than when wrapped in wax paper.”2 The sound made by wrappers, they hazard, may
have unappreciated influence.
So, although a recent Dutch study3 showed that generally you CAN judge a book by its cover, the Oxford report implies that maybe you CAN’T judge the crunch of a crisp by the crackle of its wrapper.
A Note About Electric Toothbrushes
It cannot go unmentioned that the same team, together with a Guest researcher --that is, a researcher named Guest-- published a study4 the previous year entitled “The Role of Auditory Cues in Modulating the Perception of Electric Toothbrushes.”
A Note About Crispness and Crunchiness
To scientists who study it, crispness is a technical term. It is distinct from crunchiness.
Crispness is the “Amount and pitch of sound generated when the sample is first bitten with the front teeth.” Crunchiness is the “Amount of noise generated when chewing with the back teeth.”
These definitions, and more, come from the 2000 treatise “What Makes Fruit Firm and How to Keep It That Way.”5 That same year, two of the “Firm Fruit” authors, who are at Katholieke Universiteit in Leuven, Belgium, published an instant classic of a study, “Principal Component Analysis of Chewing Sounds to Detect Differences In Apple Crispness,”6 which later influenced Zampini and Spence’s Pringles-crispness experiment, and which led to its authors’ own specific-crispness masterpiece:
Crispness Judgement of Royal Gala Apples Based on Chewing Sounds,” N. De Belie, F.R. Harker, and J. De Baerdemaeker, Biosystems Engineering, vol. 81, no. 3, March 2002, pp. 297-303.
Notes About Pringles
Pringles potato chips are not related, at least in any obvious way, with Pringle’s maneuver. Pringle’s maneuver is a medical procedure described as follows:
Pringle’s maneuver (PM: hepatic artery and portal vein clamp technique at the same time) is generally used for bleeding control in hepatectomy.
This definition is from a paper called “Effect of Prostaglandin E1, Dopamine and Dobutamine Administration for a Hepatic Venous Oxygen Saturation During Pringle’s Maneuver,” by Isao Fukuda, et al., of the National Defense Medical College, Tokorozawa, Saitama, Japan. The paper was presented on October 25, 2005 at the Annual Meeting of the American Society of Anesthesiologists.
Pringles potato chips are also not related in any obvious way to the medical condition known as Pringles disease. For an introduction to the disease, see either of these studies:
"Pringles Disease,” W. Nikolowski, Hautarzt, vol. 34, no. 4, 1983, p. 190.
“Case of Multiple Minute Fibro-Angiomata of Face and Ears (Pringles Disease, Dariers Type),” A.C. Roxburgh, Proceedings of the Royal Society of Medicine -- London, vol. 38, no. 7, 1945, pp. 331-2.
Nor are Pringles potato chips related in any obvious way to the Pringles Metamorphic Complex, a layer of rock in the central part of the Sierra de San Luis hills in Venezuela.
1. “The Role of Auditory Cues in Modulating the Perceived Crispness and Staleness of Potato Chips,” Massimiliano Zampini and Charles Spence, Journal of Sensory Studies, vol. 19, October 2004, pp. 347-63.
2. “Wrapper Influence on the Perception of Freshness in Bread,” R.L. Brown, Journal of Applied Psychology, vol. 42, 1958, pp. 257-60.
3. “Genre Categorization and Its Effect on Preference for Fiction Books,” Ronald A.M.P. Piters and Mia J.W. Stokmans, Empirical Studies of the Arts, vol. 18, no. 2, 2000, pp. 159-66.
4. “The Role of Auditory Cues in Modulating the Perception of Electric Toothbrushes,” Massimiliano Zampini, S. Guest, and Charles Spence, Dental Research, vol. 82, no. 11, 2003, pp. 929-32.
5. “What Makes Fruit Firm and How to Keep It That Way,” F. Roger Harker, Richard Volz, Jason W. Johnston, Ian C. Hallett and Nele De Belie, a paper presented at the 16th Annual Postharvest Conference, Yakima, Washington, March 14-15, 2000. (Nele De Belie is at the Magnel Laboratory for
Concrete Research at Ghent University.)
6. “Principal Component Analysis of Chewing Sounds to Detect Differences in Apple Crispness,” N. De Belie, V. De Smedt and J. De Baerdemaeker, Postharvest Biology and Technology, vol. 18, no. 2, 2000, pp. 109-19.
This article is republished with permission from the May-June 2006 issue of the Annals of Improbable Research. You can download or purchase back issues of the magazine, or subscribe to receive future issues. Or get a subscription for someone as a gift!
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