J. Neurophysiol. 94, 1655-1658, 2005. First published April 20, 2005; doi:10.1152/jn.01226.2004.

Microsecond precision of phase delay in the auditory system of the barn owl.

H. Wagner, S. Brill, R. Kempter, and C. E. Carr.

The auditory system encodes time with sub-millisecond accuracy. To shed new light on the basic mechanism underlying this precise temporal neu- ronal coding, we analyzed the neurophonic potential, a characteristic multiunit response, in the barn owl's nucleus laminaris. We report here that the relative time measure of phase delay is robust against changes in sound level, with a precision sharper than 20 s. Absolute measures of delay, such as group delay or signal-front delay, had much greater temporal jitter, for example due to their strong depen- dence on sound level. Our findings support the hypothesis that phase delay underlies the sub-millisecond precision of the representation of interaural time difference needed for sound localization.

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