Acoustics in the News (Fall 2009)

From Fall 2009, The acoustical society of America

• Ear identification scan could one day be a commonplace technique to identify a caller on the telephone, according to a technology note in the 11 April issue of New Scientist. The concept relies on the fact that the ear not only senses sound but also makes noises of its own, albeit at a level only detectable by sensitive microphones. Such otoacoustic emissions (OAEs) emanate from within the cochlea, and they are thought to be produced by the motion of the hair cells within the outer part of the cochlea. Sounds entering the ear cause these hair cells to vibrate, and these vibrations are converted to electrical signals. OAEs can be provoked when a series of clicks is played into the ear. The returning sound emissions comprise signals between 0 and 5 kHz. The clicks could be supplied by a telephone to identify the person at the other end.
• A computer chip modeled on the human ear could be used in universal receivers for radio-frequency signals, a technology note in the 13 June issue of New Scientist tells us. Devices such as cellphones or FM radios are generally tuned to only a narrow frequency band. The new devices, inspired by the network of hair cells in the ear, can pick up a wide range of frequencies. A network of transistors in the device act like hair cells in the ear. Frequencies ranging from 600 MHz to 8 GHz requires no more electrical power than single-frequency receivers.
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