Frequency glides in the impulse responses of auditory-nerve fibers

Previous reports of frequency modulations, or glides, in the impulse respon ses of the auditory periphery have been limited to analyses of basilar-memb rane measurements and responses of auditory-nerve (AN) fibers with best fre quencies (BFs) greater than 1.7 kHa. These glides increased in frequency as a function of time. In this study, the instantaneous frequency as a functi on of time was measured for impulse responses of AN fibers in the cat with a range of BFs (250-4500 Hz). Impulse responses were estimated from respons es to wideband noise using the reverse-correlation technique. The impulse r esponses had increasing frequency glides for fibers with BFs greater than 1 500 Hz, nearly constant frequency as a function of time for BFs between 750 and 1500 Hz, and decreasing frequency glides for BFs below 750 Hz. Over th e levels tested, the glides for fibers at all BFs were nearly independent o f stimulus level, consistent with previous reports of impulse responses of the basilar membrane and AN fibers. Implications of the different glide dir ections observed for different BFs are discussed, specifically in relation to models for the auditory periphery as well as for the derivation of impul se responses for the human auditory periphery based on psychophysical measu rements. (C) 1999 Acoustical Society of American. [S0001-4966(99)03204-X].