SPECTRAL COMPOSITION OF EATING SOUNDS GENERATED BY CRISPY, CRUNCHY AND CRACKLY FOODS

Separate air and bone conducted food sounds generated by six subjects biting into eight foods were recorded and analysed by a fast Fourier transform (FFT) signal analyser. A panel of 60 subjects classified the 8 foods according to their texture: crispy, crunchy and crackly and these textural characteristics were described by spectral characteristics of biting sounds. Crispy foods (such as extruded flat breads) were found to generate high pitched sounds that show a high level of frequencies higher than 5 kHz, especially for air conduction. Crunchy foods (such as raw carrot) generate low pitched sounds with a characteristic peak on frequency range 1.25 to 2 kHz for air conduction. And crackly foods (such as dry biscuits) generate low pitched sounds with a high level of bone conduction. We hypothesize that discrimination between crunchy and crackly foods could be due to vibrations propagated by bone conduction that also generated vibrotactile sensations.