Submitted on December 1, 2004
Accepted on April 7, 2005
Microsecond precision of phase delay in the auditory system of the barn owl
Hermann Wagner*, Sandra Brill, Richard Kempter, and Catherine E. Carr
* To whom correspondence should be addressed. E-mail: wagner{at}bio2.rwth-aachen.de.
The auditory system encodes time with sub-millisecond accuracy. To shed new light on the basic mechanism underlying this precise temporal neuronal 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 microseconds. Absolute measures of delay, such as group delay or signal-front delay, had much greater temporal jitter, for example due to their strong dependence 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.
