Narrow-band acoustic signals emitted by chinchilla ears after noise exposure

Acoustic search in 21 ears of 17 chinchillas exposed to a variety of high-intensity sounds revealed two instances of a spontaneous and continuous narrow-band acoustic signal emanating from the ear. These signals, found in the 4–7 kHz region after exposure to an octave band of noise centered at 0.5 kHz, could be suppressed by external tones. The frequency selectivity and time course of the suppression effect suggest that these otoacoustic emissions originate from a vibratory source in the cochlea.