Temporal weighting of binaural information at low frequencies: Discrimination of dynamic interaural time and level differences

Abstract

The importance of sound onsets in binaural hearing has been addressed in many studies, particularly at high frequencies, where the onset of the envelope may carry much of the useful binaural information. Some studies suggest that sound onsets might play a similar role in the processing of binaural cues [e.g., fine-structure interaural time differences (ITD)] at low frequencies. This study measured listeners' sensitivity to ITD and interaural level differences (ILD) present in early (i.e., onset) and late parts of 80-ms pure tones of 250-, 500-, and 1000-Hz frequency. Following previous studies, tones carried static interaural cues or dynamic cues that peaked at sound onset and diminished to zero at sound offset or vice versa. Although better thresholds were observed in static than dynamic conditions overall, ITD discrimination was especially impaired, regardless of frequency, when cues were not available at sound onset. Results for ILD followed a similar pattern at 1000 Hz; at lower frequencies, ILD thresholds did not differ significantly between dynamic-cue conditions. The results support the "onset" hypothesis of Houtgast and Plomp [(1968). J. Acoust. Soc. Am. 44, 807-812] for ITD discrimination, but not necessarily ILD discrimination, in low-frequency pure tones.

Strength of onset and ongoing cues in judgments of lateral position

“…These studies have shown less than expected improvement as a function of stimulus duration, suggesting that the earliest part of the signal contributes more information than later parts (e.g., Houtgast and Plomp, 1968;Hafter and Dye, 1983). Other studies have used time varying ITDs and ILDs and have obtained discrimination results supporting greater sensitivity to these cues near signal onset (Stecker and Brown, 2012;Stecker and Bibee, 2014;Diedesch and Stecker, 2015). Yost (2016), using a localization paradigm, recently showed no improvement in accuracy as duration increasing from 25 to 450 ms. Other studies have directly probed ITD or ILD sensitivity using temporal segments embedded within a longer noise and have found best sensitivity at onset, followed by a period of very poor sensitivity, followed by gradual improvement in sensitivity tens of ms after onset (Zurek, 1980;Akeroyd and Bernstein, 2001).…”

Temporal weighting functions for interaural time and level differences. V. Modulated noise carriers

“…Although this series of papers has focused on periodically modulated high-frequency sounds, other studies have used alternative approaches to also demonstrate correlates of onset dominance at lower frequencies and in pure tones (Dietz et al, 2013;Stecker and Bibee, 2014;Diedesch and Stecker, 2015). Together, results suggest that onset dominance is a general phenomenon of binaural hearing, impacting a wide range of frequencies and cue types, including fine-structure ITD, envelope ITD, and ILD (Stecker, 2016b).…”

Spectrotemporal weighting of binaural cues: Effects of a diotic interferer on discrimination of dynamic interaural differences

“…Weighting across frequency is demonstrated in studies of "binaural interference" that reveal the dominance of low-over high-frequency ITD cues and high-over low-frequency ILD cues (McFadden and Pasanen, 1976;Heller and Trahiotis, 1995;Heller and Richards, 2010). Weighting over time is demonstrated by the dominance of onset over later-arriving binaural cues in lowfrequency pure tones (Stecker and Bibee, 2014;Diedesch and Stecker, 2015) and rapidly modulated sounds (Hafter and Dye, 1983;Saberi, 1996;Freyman et al, 1997;Stecker, 2014). Each of these examples appears consistent with the dominance of more reliable over less reliable cues.…”