Psychophysical and physiological assessment of the representation of high‐frequency spectral notches in the auditory nerve

High‐frequency spectral notches such as those generated by the pinna are useful for sound localization. Because their center frequency (6–8 kHz) is beyond the cutoff of phase locking, the common view is that the internal representation of such notches does not involve the timing of action potentials and that, instead, they must be exclusively represented in terms of auditory nerve rate profiles. Recently, we [A. Alves‐Pinto and E. A. Lopez‐Poveda, J. Acoust. Soc. Am. 118, 2548 (2005)] have shown that the threshold notch depth for discriminating between a flat‐spectrum noise and a noise with a square spectral notch centered at 8 kHz varies nonmonotonically with increasing sound level, and that discrimination is worst for levels around 80 dB SPL. Here, we show that the information in the auditory nerve rate profiles is insufficient to account for this psychophysical result, and that temporal information is almost certainly used for discriminating between noise bursts with and without high‐frequency spectral notches.