Magnitude and phase-frequency response to singletones in the auditory nerve

In this paper we describe magnitude and phase measurements obtained from primary single unit recordings in the cat auditory nerve. Levels range from threshold to 100dB SPL, with frequencies from 0.1-30.0 kHz. The upper limit on the phase measurements waslimited by the loss of neural phase locking at 4—5 kHz. For each unit, the frequency tuning curve (FTC) was measured by the methocPof Kiang and Moxon [M. C. Liberman, J. Acoust. Soc. Am. 63, 442–445 (1978)] to establish the threshold frequency response of the unit. Data from several selected animals, organized by characteristic frequenc(CF), are presented showing phase response, group delay, frequency tuning, and tuningslope for each CF range. The major emphasis in this paper is on the “linear”aspects of the data as characterized by the filter properties of the single unit response, however a number of nonlinear (level-dependent) effects are described. Data are presented showing the phase response normalized by the cochlear microphonic (CM)recorded at theround window membrane. This normalization simplifies the phase data since it produces a, constant phase slope with respect to frequency constant group of America.