Meeting Abstract
Many animals localize sound sources using cues derived from sounds arriving at two ears that are segregated in space. Animals can also localize sounds using monaural cues, such as location-based spectral or amplitude profiles. Spectral and amplitude profiles are thought to be generated by the soft tissue of the pinna in mammals and by soft tissue and the facial ruff in barn owls (Tyto alba). Asymmetry of ear placement in the skull, in addition to soft tissue asymmetry, is found in only a few species, such as the Northern saw-whet owls (Aegolius acadicus). We investigated the effect of spatial location on monaural responses in the Northern saw-whet owl, using auditory evoked potentials to measure the response of each ear to sound sources placed in different locations around the head. The response amplitude changed most dramatically with elevation and the response latency changed most dramatically with azimuth. Furthermore, we found that sensitivity was greatest in the spatial locations above the beak and in front of the head. Sensitivity dropped off dramatically as the sound source was moved behind the head. This directional sensitivity should improve sound detection and processing of prey cues in front of the head, while reducing the effect of noise generated during flight.
