Forward masking of click responses in auditory nerve fiber as a function of CF

Discharges of auditory nerve fibers to broadband clicks were masked with tone bursts (rise time, 1 ms; duration, 30 ms) of 4,8, or 13 kHz. The tone burst preceded the click by 10 ms, thus the click response was subjected to “forward masking.” Click intensity was set 30 dB above the intensity which produced a just detectable N1 averaged response (256 epochs). After determining CF for each fiber, a PST histogram of the unit's response to the click at the standard intensity was taken. Tone burst frequency was then set at 4, 8, or 13 kHz and PST histograms to the click were recorded as the intensity of the tone bursts was increased in 10 dB steps. The reduction in click responses by each forward masker was measured for units distributed over a range of CF for constant masker intensities. The discharges of units with CFs near the masker frequency are reduced by the greatest amount, those from units with CFs below masker frequency may show an increase in discharges to the click. [Supported by NSF, No. BNS‐77‐16...