Binaural and monaural auditory filter bandwidths and time constants in probe tone detection experiments

Abstract

Auditory filter bandwidths and time constants were obtained with five normal-hearing subjects for different masker configurations both in the frequency and time domain for monaural and binaural listening conditions. Specifically, the masking level in the monaural condition and the interaural correlation in the binaural conditions, respectively, was changed in a sinusoidal, stepwise, and rectangular way in the frequency domain. In the corresponding experiments in the time domain, a sinusoidal and stepwise change of the masker was performed. From these results, a comparison was made across conditions to evaluate the influence of the factors "shape of transition," "monaural versus binaural," "frequency domain versus time domain," and "subject." Also, the respective data from the literature were considered using the same model assumptions and fitting strategy as used for the current data. The results indicate that the monaural auditory filter bandwidths and time constants fitted to the data are consistent across conditions both for the data included in this study and the data from the literature. No consistent relation between individual auditory filter bandwidths and time constants were found across subjects. For the binaural conditions, however, considerable differences were found in estimates of the bandwidths and time constants, respectively, across conditions. The reason for this mismatch seems to be the different detection strategies employed for the various tasks that are affected by the consistency of binaural information across frequency and time. While monaural detection performance appears to be modeled quite well with a linear filter or temporal integration window, this does not hold for the binaural conditions where both larger bandwidth and time constant estimates are found.

The binaural temporal window in adults and children

“…The time constant of the binaural temporal window is estimated, in part, from the steepness with which the detection thresholds of the brief signals change with respect to the temporal occurrence of the signal relative to the interaural phase transition of the masking noises. Estimates of binaural time constants using this method are longer than typical estimates of monaural time constants under analogous stimulus conditions (Kollmeier and Gilkey, 1990;Holube et al, 1998), consistent with the proposal that the binaural system is "sluggish" (Grantham and Wightman, 1978;Grantham and Wightman, 1979). …”

“…This reflects an assumption that the maximum MLD in the dynamic masker conditions is equal to the MLD obtained in the steady masker conditions, but that all thresholds may suffer from the presence of the masker phase transition, those based on binaural cues and those based on monaural cues alike. As in previous studies using this fitting technique (Kollmeier and Gilkey, 1990;Holube et al, 1998), three parameters were allowed to vary: time constants for the lagging and leading edges of the window (τ1 and τ2) and an estimate of overall processing efficiency (L M ). As in Kollmeier and Gilkey (1990), it was assumed that the binaural temporal window was centered on the onset of the Sπ signal in the NoNπ masker and on the offset of the Sπ signal in the NπNo masker.…”

“…The present study investigated the binaural temporal window (Kollmeier and Gilkey, 1990;Culling and Summerfield, 1998;Holube et al, 1998;Bernstein et al, 2001) in adults and school-aged children. The binaural temporal window refers to the temporal epoch during which the auditory system integrates information related to binaural difference cues.…”

“…Experiments on the binaural temporal window are often performed in the context of the masking-level difference (MLD) paradigm (Hirsh, 1948), where the signal and the masker are presented to the two ears with different interaural phase characteristics. In the paradigm used here Kollmeier and Gilkey, 1990;Holube et al, 1998), the binaural temporal window is measured using a brief, interaurally out-of-phase signal (Sπ) as a function of the temporal position of the signal with respect to an abrupt interaural phase transition of the noise masker. This transition is either from in phase to out of phase (NoNπ) or from out of phase to in phase (NπNo).…”

The Time Course of Binaural Masking in the Inferior Colliculus of Guinea Pig Does Not Account for Binaural Sluggishness

“…In this experiment, we used a step transition between N0 and N or vice versa, which are comparable to the experiments of Holube et al (1998) and Kollmeier and Gilkey (1990). These experiments showed ERDs of around 55 ms; which are in the middle of the range observed.…”