Temporal weighting of interaural time differences in low frequency noise presented at low signal-to-noise ratio

Abstract

Discrimination of interaural time difference (ITD) improves with increasing duration of a target stimulus, but more slowly than expected if ITD sensitivity was temporally uniform over the sound duration. Houtgast and Plomp [JASA 44, 807–812 (1968)] thus argued for nonuniformal temporal weighting of ITD, in which sound onsets dominate listeners' ITD judgments. That theory is well supported by recent work. Additional data reported by Houtgast and Plomp suggest more uniform weighting in the presence of masking noise at 5 dB signal-to-noise ratio (SNR). The current study measured ITD thresholds for 500 Hz octave-band noise targets with ITD fixed over duration (condition “RR”) or changing linearly from zero to peak value (condition “0R”) or vice versa ( “R0”). Targets were presented in the presence or absence of a continuous 500Hz octave-band masker (5dB SNR). Comparison data were obtained using 500 Hz pure-tone targets across identical ITD and masker configurations (Diedesch and Stecker, 2014, Assoc. Res. Otolaryngol.). ITD detection with pure-tone targets did not appear to benefit (in terms of threshold-vs-duration slopes) from masking noise as in Houtgast and Plomp (1968). Other stimulus conditions that more closely replicate the conditions of that study (i.e., noise targets) are discussed. [Work supported by NIH R01 DC011548.]