Temporal weighting functions for interaural time and level differences. II. The effect of binaurally synchronous temporal jitter.

Recent work has demonstrated that sensitivity to interaural time differences (ITD) carried by high-rate cochlear implant pulse trains or analogous acoustic signals can be enhanced by imposing random temporal variation on the stimulus rate [see Goupell et al. (2009). J. Acoust. Soc. Am. 126, 2511-2521]. The present study characterized the effect of such "temporal jitter" on normal-hearing listeners' weighting of ITD and interaural level differences (ILD) applied to brief trains of Gabor clicks (4 kHz center frequency) presented at nominal interclick intervals (ICI) of 1.25 and 2.5 ms. Lateral discrimination judgments were evaluated on the basis of the ITD or ILD carried by individual clicks in each train. Random perturbation of the ICI significantly reduced listeners' weighting of onset cues for both ITD and ILD discrimination compared to corresponding isochronous conditions, consistent with enhanced sensitivity to post-onset binaural cues in jittered stimuli, although the reduction of onset weighting was not statistically significant at 1.25 ms ICI. An additional analysis suggested greater weighting of ITD or ILD presented following lengthened versus shortened ICI, although weights for such "gaps" and "squeezes" were comparable to other post-onset weights. Results are discussed in terms of binaural information available in jittered versus isochronous stimuli.

[1]  Observer weighting of level and timing cues in bilateral cochlear implant users , 2008 .

[2]  E R Hafter,et al.  Detection of interaural differences of intensity in trains of high-frequency clicks as a function of interclick interval and number. , 1983, The Journal of the Acoustical Society of America.

[3]  E R Hafter,et al.  Detection of interaural differences of time in trains of high-frequency clicks as a function of interclick interval and number. , 1983, The Journal of the Acoustical Society of America.

[4]  Kourosh Saberi,et al.  A population study of the precedence effect , 2004, Hearing Research.

[5]  Piotr Majdak,et al.  Enhancing sensitivity to interaural time differences at high modulation rates by introducing temporal jitter. , 2009, The Journal of the Acoustical Society of America.

[6]  Bruce G. Berg,et al.  Analysis of weights in multiple observation tasks , 1989 .

[7]  L. A. Jeffress,et al.  Two-image lateralization of tones and clicks. , 1968, The Journal of the Acoustical Society of America.

[8]  T N Buell,et al.  Restarting the adapted binaural system. , 1990, The Journal of the Acoustical Society of America.

[9]  G Christopher Stecker,et al.  A recency effect in sound localization? , 2009, The Journal of the Acoustical Society of America.

[10]  G. C. Stecker,et al.  Temporal weighting in sound localization. , 2002, The Journal of the Acoustical Society of America.

[11]  Andrew D Brown,et al.  Temporal weighting of binaural cues revealed by detection of dynamic interaural differences in high-rate Gabor click trains. , 2010, The Journal of the Acoustical Society of America.

[12]  L. A. Jeffress,et al.  Individual Differences in Sensitivity to Interaural Differences in Time and Level 1 , 1973, Perceptual and motor skills.

[13]  B. Delgutte,et al.  Neural coding of ITD with bilateral cochlear implants: Effects of auditory experience , 2009 .

[14]  R L Freyman,et al.  Onset dominance in lateralization. , 1997, The Journal of the Acoustical Society of America.

[15]  William M Hartmann,et al.  Interaural level differences and the level-meter model. , 2002, The Journal of the Acoustical Society of America.

[16]  R. Tyler,et al.  Speech perception, localization, and lateralization with bilateral cochlear implants. , 2003, The Journal of the Acoustical Society of America.

[17]  Katrin Krumbholz,et al.  Buildup and breakdown of echo suppression for stimuli presented over headphones-the effects of interaural time and level differences. , 2002, The Journal of the Acoustical Society of America.

[18]  D L Neff Signal properties that reduce masking by simultaneous, random-frequency maskers. , 1995, The Journal of the Acoustical Society of America.

[19]  R. V. van Hoesel,et al.  Observer weighting of level and timing cues in bilateral cochlear implant users. , 2008, The Journal of the Acoustical Society of America.

[20]  Effects of center frequency and rate on the sensitivity to interaural delay in high-frequency click trains. , 2009, The Journal of the Acoustical Society of America.

[21]  K Saberi,et al.  Observer weighting of interaural delays in filtered impulses , 1996, Perception & psychophysics.

[22]  Robert F Labadie,et al.  Interaural Time and Level Difference Thresholds for Acoustically Presented Signals in Post-Lingually Deafened Adults Fitted with Bilateral Cochlear Implants Using CIS+ Processing , 2007, Ear and hearing.

[23]  Piotr Majdak,et al.  Binaural jitter improves interaural time-difference sensitivity of cochlear implantees at high pulse rates , 2008, Proceedings of the National Academy of Sciences.

[24]  G. C. Stecker,et al.  Temporal weighting of interaural time and level differences in high-rate click trains. , 2010, The Journal of the Acoustical Society of America.

[25]  Kourosh Saberi,et al.  Precedence-effect thresholds for a population of untrained listeners as a function of stimulus intensity and interclick interval. , 2003, The Journal of the Acoustical Society of America.

[26]  E R Hafter,et al.  The combination of interaural time and intensity in the lateralization of high-frequency complex signals. , 1990, The Journal of the Acoustical Society of America.

[27]  S. J. Griffin,et al.  Listeners' sensitivity to "onset/offset" and "ongoing" interaural delays in high-frequency, sinusoidally amplitude-modulated tones. , 2008, The Journal of the Acoustical Society of America.

[28]  G. Henning Detectability of interaural delay in high-frequency complex waveforms. , 1974, The Journal of the Acoustical Society of America.

[29]  Andrew D Brown,et al.  Temporal weighting of interaural time and level differences in high-rate click trains. , 2010, The Journal of the Acoustical Society of America.

[30]  Ruth Y Litovsky,et al.  Effect of age at onset of deafness on binaural sensitivity in electric hearing in humans. , 2010, The Journal of the Acoustical Society of America.