Recovery of detection probability following sound exposure: Comparison of physiology and psychophysics

Detection probability for 1-kHz test tone-bursts was estimated at 1-sec intervals following exposure of subjects to a 1-kHz continuous tone. Immediately after the exposure tone, detection probability is depressed. Recovery to preexposure probability is well fit by a single rising exponential function. These psychophysical data are compared with the recovery of discharge rate in single fibers of the cat’s auditory nerve following similar exposures. For both sets of data the time constant of recovery decreases with increasing test tone-burst level; the decrease is significantly faster for detection probability recovery than for recovery of discharge rate. This difference can be accounted for by a simple model relating discharge rate in ensembles of auditory-nerve fibers to detection probability. Whereas the recovery time constant of discharge rate increases monotonically with exposure level, the recovery time constant of detection probability increases up to about 40 dB SPL and then decreases as exposure level is increased. We could not explain this difference on the basis of existing data.