Release from masking in fluctuating background noise in a songbird's auditory forebrain

Fluctuations in the ubiquitous masking background noise can be exploited by the vertebrate auditory system to considerably improve signal detection. Here we demonstrate neuronal masking release in amplitude-modulated background noise on the level of the European starling's auditory forebrain, an area that is the analogue of the mammalian primary auditory cortex. Tone-evoked responses in the presence of modulated and unmodulated maskers were recorded in unrestrained birds via radiotelemetry. Based on a rate code, the average amount of neuronal masking release was similar to that observed in a psychoacoustic study on the starling with stimuli confined to a single auditory filter. The results suggest that the neurons exploited predominantly temporal features of the acoustic background to improve signal detection.