Subject: Re: ITDs From: John Culling <cullingj@xxxxxxxx> Date: Wed, 23 Sep 2009 09:20:22 +0100 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>ITD is not an effective cue at high frequencies for pure tones, but other waveforms - noise bands, high-pass-filtered clicks and particularly "transposed stimuli" (cf. JASA papers by Bernstein, van de Par etc.) - it is still effective. The reason it is not effective for pure tones is presumed to be the fact that there is a loss of phase-locking to the fine structure of the stimulating waveform at stages of the auditory system that precede binaural interaction. It is known, for instance, that the capacitance of inner hair cells prevents their intracellular potential from following carrier frequencies in excess of 4-5 kHz in mammals. This results in a corresponding loss of encoding on the auditory nerve. Carrier ITDs cease to be effective above about 1500 Hz, however, so there may be further losses upstream. ITDs encoded by the waveform envelope (which are present for noises, clicks etc.) are not subject to this limitation, John.