Our laboratory's long-term goal is to understand how the auditory system allows us to listen selectively to the sound of interest amidst sources of interference. Using the auditory system of the barn owl (Tyto alba), with its topographic maps of space, we have been studying the effects of background noise and echoes on spatial resolution. Auditory events, however, generally unfold in time, and the auditory system must keep track of temporal changes in the features of sounds. In this project, we ask: How well does the auditory system encode time-varying signals in a cluttered environment? Behaviorally salient cues in the owl's environment, such as sounds of prey and many of its vocalizations (e.g, the threat call) consist of broadband signals with complex temporal structure. The neurons of the bran owl's inferior colliculus were recently found to adept at tracking the temporal structure of such complex waveforms in addition to being selective for the source's location. In this project, we examined how this temporal firing pattern is affected by noise. Parallel studies of behavior and neurophysiology are carried out in Aims 1 and 2, and in Aim 3, we combine the two methods in a novel attempt to record neuronal responses from the awake, behaving bird.