Effect of mid-term adaptation on pure-tone detection

Abstract

International audiencePerformance in detecting a 50 ms pure-tone signal in a longer tone-burst masker was evaluated as a function of the delay between masker and signal onset. Delays from 500 ms to 5 s were used, and detection was measured in terms of sensitivity d'. Performance was also mt;asured for a continuous masker. In a first experiment, the masker and the signal had the same frequency (500, 1000, 2000, 4000 and 8000Hz). In this case, sensitivity increased with delay for high frequencies and for high masker levels. In a second experiment, the masker and the signal had different frequencies; the masker was set at 4 kHz and the signal frequency was inside and outside the critical band of the masker. For this second case, the results depended on masker level and signal frequency: increasing the delay for a 50 dB SL masker did not improve detection; at 80 dB SPL, however, delaying the signal improved detection for signal frequencies close to the masker frequency. The assumption is made that the improved detection for long durations of the masker originates from a long-term decrease in the firing rate of the auditory nerve fibers