In nature, sounds from a source of interest often arrive at the ears followed closely by reflections from objects in the environment. Despite the superposition of direct and reflected sound, which can degrade sound-localization cues, listeners are able to localize and characterize the true source of the sound. The precedence effect refers to a cluster of perceptual phenomena related to the extraction of valid directional cues from reverberant sounds. I concentrate on one component, localization dominance, in which subjects, when presented with sounds from two loci in rapid succession, tend to perceive a single sound coming from the location of the leading source. The barn owl is a nocturnal predator that tracks its prey guided by a midbrain map of auditory space. A close inspection of how space-specific neurons respond to a lagging sound reveals a brief burst in spike rate, evoked by the onset of the reflection, followed by a second burst, evoked at the offset of the leading sound. Either burst may be the signal that prompts owls to localize the reflection. I propose using neurophysiological and psychophysical experiments to determine which of these two spike bursts is salient and which burst most closely parallels the time course of localization dominance. ? ? ?
| Donovan, Jeff M; Nelson, Brian S; Takahashi, Terry T (2012) The contributions of onset and offset echo delays to auditory spatial perception in human listeners. J Acoust Soc Am 132:3912-24 |
| Nelson, Brian S; Takahashi, Terry T (2010) Spatial hearing in echoic environments: the role of the envelope in owls. Neuron 67:643-55 |
| Nelson, Brian S; Takahashi, Terry T (2008) Independence of echo-threshold and echo-delay in the barn owl. PLoS One 3:e3598 |
