Assessing the effects of temporal coherence on auditory stream formation through comodulation masking release

Abstract

Recent studies of auditory streaming have suggested that repeated synchronous onsets and offsets over time, referred to as "temporal coherence," provide a strong grouping cue between acoustic components, even when they are spectrally remote. This study uses a measure of auditory stream formation, based on comodulation masking release (CMR), to assess the conditions under which a loss of temporal coherence across frequency can lead to auditory stream segregation. The measure relies on the assumption that the CMR, produced by flanking bands remote from the masker and target frequency, only occurs if the masking and flanking bands form part of the same perceptual stream. The masking and flanking bands consisted of sequences of narrowband noise bursts, and the temporal coherence between the masking and flanking bursts was manipulated in two ways: (a) By introducing a fixed temporal offset between the flanking and masking bands that varied from zero to 60 ms and (b) by presenting the flanking and masking bursts at different temporal rates, so that the asynchronies varied from burst to burst. The results showed reduced CMR in all conditions where the flanking and masking bands were temporally incoherent, in line with expectations of the temporal coherence hypothesis.

How We Hear: The Perception and Neural Coding of Sound

“…If the sequences are presented coherently and synchronously, they will tend to form a single stream, even if they differ along other dimensions (Micheyl et al 2013a). Note that temporal coherence goes beyond simple synchrony: Although sound elements are generally perceived as belonging to a single source if they are gated synchronously (e.g., Bregman 1990), when synchronous sound elements are embedded in a longer sequence of similar sounds that are not presented synchronously or coherently, no grouping occurs, even between the elements that are synchronous (Christiansen & Oxenham 2014, Elhilali et al 2009).…”

Temporal coherence structure rapidly shapes neuronal interactions

“…Temporal coherence also explained why a few synchronous tone sequences perceptually pop-out even in the midst of a dense background of random tones4, and why prominent electroencephalogram responses to these synchronous tones emerge even in the absence of other distinguishing features such as global changes in signal power or local tone densities56. Finally, temporal coherence has also been demonstrated to play a role in co-modulation masking release78 and its dynamics have recently been imaged in the primary auditory cortex9.…”

Developmental Conductive Hearing Loss Reduces Modulation Masking Release

“…Both MMR and MMR+ are strongly reduced in hearing-impaired individuals and cochlear-implant users ( Bacon, Opie, & Montoya, 1998 ; Ihlefeld, Shinn-Cunningham, & Carlyon, 2012 ; Léger, Reed, Desloge, Swaminathan, & Braida, 2015 ; Nelson, Jin, Carney, & Nelson, 2003 ; Oxenham & Kreft, 2014 ; Pierzycki & Seeber, 2014 ; Zirn, Hempel, Schuster, & Hemmert, 2013 ). Although peripheral dysfunction can explain much of this impairment, MMR is thought to arise from a combination of peripheral and CNS mechanisms ( Christiansen & Oxenham, 2014 ; Dau, Ewert, & Oxenham, 2009 ; Dau, Piechowiak, & Ewert, 2013 ). The premise of several successful MMR models is that temporal correlation between masker bands at different frequencies makes it easier for listeners to detect a tone in the energetic dips of a fluctuating masker ( Dau et al., 2013 ; Pressnitzer, Meddis, Delahaye, & Winter, 2001 ), a computation that cannot be performed in the cochlea.…”