Test of a model of auditory object formation using intensity and interaural time difference discrimination

Abstract

A model of auditory object formation and an experimental evaluation of the model are described. Specifically, predictions for intensity discrimination and interaural time difference discrimination for the central component of a three-component harmonic complex are evaluated empirically. The onset time of the central, target component is varied relative to the onset times of the remaining, interferer components in order to vary the degree of fusion (versus perceptual segregation) of the target and the interferers. The model, which is based on the idea of attenuation of the components in the nonattended auditory image (in the case of segregated images), predicts lower sensitivity to information at the target component for the fused versus segregated target, and equal sensitivities for completely segregated targets and targets presented in isolation. Results are presented for four subjects with component frequencies of 400, 600, and 800 Hz and with onset time differences of 0 or 250 ms. The target duration was always 100 ms and offset times were the same for all components. The subjective results were as expected, with synchronous onsets yielding one sound object, and asynchrony of the central component yielding two sound objects. Also, the empirical results on interference in the synchronous case were in qualitative agreement with the above predictions. However, significantly more interference was found than was predicted for both synchronous and asynchronous conditions. In fact, the amount of interference found contradicts the simple attenuation model of object formation.

Six Degrees of Auditory Spatial Separation

“…Secondly, the difference in fundamental frequencies, the harmonic structure of each token, and the differences in onset time all combine to ensure that the spectral components would be appropriately grouped to each token (e.g., Darwin 1981, reviewed in Darwin 2008. The computation of the spatial location of each token has been shown to be dependent on the spatial cues present in the grouped components (Woods and Colburn 1992;Hill and Darwin 1996). Consistent with this, the lack of spatial interactions between two concurrent speech stimuli has been shown previously (Simpson et al 2006;Kopco et al 2010).…”

Listening to every other word: Examining the strength of linkage variables in forming streams of speech

“…According to Yost ͑1991, 2008͒, sound source determination is fundamental to the perceptual organization of the auditory environment and to making sense of the information the sources convey. Individual sounds are sometimes referred to as auditory "objects," which reflects the view that sounds are typically segmented into discrete perceptual elements ͑e.g., Woods and Colburn, 1992;Griffiths and Warren, 2004;and Shinn-Cunningham, 2008͒. When a sequence of related elements occurs the listener may perceive an auditory "stream" that can be segregated from other unrelated sounds.…”

A function for binaural integration in auditory grouping and segregation in the inferior colliculus

“…Psychophysical studies have demonstrated that the percept of the pitch of a harmonic complex is independent of the distribution of individual resolved harmonics between the ears (Beerends and Houtsma 1986;Culling and Summerfield 1995;Darwin and Hukin 1999;Woods and Colburn 1992). This indicates that there exists a binaural neural site at which the components between the two ears are analyzed together.…”