Forward masking enhances the auditory brainstem response in the free-tailed bat, Tadarida brasiliensis, during a critical time window for sonar reception.

Forward masking is a widespread auditory phenomenon in which the response to one sound transiently reduces the response to a succeeding sound. This study used auditory brainstem responses to measure temporal masking effects in the free-tailed bat, Tadarida brasiliensis. A digital subtraction protocol was used to isolate responses to the second of a pair of pulses varying in interval, revealing a suppression phase lasting <4 ms followed by an enhancement phase lasting 4-15 ms during which the ABR waveform was amplified up to 100%. The results suggest echolocating bats possess adaptations for enhancing sonar receiver gain shortly after pulse emission.