Modeling comodulation masking release using an equalization-cancellation mechanism

Abstract

This study presents an auditory processing model that accounts for the perceptual phenomenon of comodulation masking release (CMR). The model includes an equalization-cancellation (EC) stage for the processing of activity across the audio-frequency axis. The EC process across frequency takes place at the output of a modulation filterbank assumed for each audio-frequency channel. The model was evaluated in three experimental conditions: (i) CMR with four widely spaced flanking bands in order to study pure across-channel processing, (ii) CMR with one flanking band varying in frequency in order to study the transition between conditions dominated by within-channel processing and those dominated by across-channel processing, and (iii) CMR obtained in the “classical” band-widening paradigm in order to study the role of across-channel processing in a condition which always includes within-channel processing. The simulations support the hypothesis that within-channel contributions to CMR can be as large as 15dB. The across-channel process is robust but small (about 2–4dB) and only observable at small masker bandwidths. Overall, the proposed model might provide an interesting framework for the analysis of fluctuating sounds in the auditory system.

Superposition of masking releases

“…an inhibition of a inhibitory narrowly tuned cell as hypothesized in Meddis et al (2002). In a recent effective model of CMR a similar strategy was used as in the present study by applying zero weights to channels at and close to the signal frequency for the hypothesized equalization-cancellation process (Piechowiak et al 2007). …”

“…At such a spectral distance, a model using compression predicts CMR only if an unrealistic broad peripheral filter is assumed (Buschermöhle et al 2007) and a model using modulation cues also predicts negligible CMR (Piechowiak et al 2007). A substantial effect of suppression on CMR was found for low-level signalcentred bands and high-level flanking bands.…”

Effects of the selective disruption of within- and across-channel cues to comodulation masking release

“…Several models have been proposed to account for a wide range of psychoacoustic data in CMR experiments (e.g., Verhey et al, 1999;Buschermöhle et al, 2007;Piechowiak et al, 2007). In general, such models have incorporated very clear distinctions between within-and acrosschannel processes.…”

“…This fall may partly reflect "across-channel" processes, that is, the auditory system's ability to make comparisons of the outputs of different auditory filters (Schooneveldt and Moore, 1989;Buus, 1985;. However, larger CMRs are often observed when the FBs are centered close to the OFB (Schooneveldt and Moore, 1987;Piechowiak et al, 2007;Grose et al, 2009;Goldman et al, 2010), an effect that is thought to be based at least partly on "within-channel" cues at the output of an auditory filter centered at or close to the signal frequency (Schooneveldt and Moore, 1989;Verhey et al, 1999;Goldman et al, 2011).…”

Effects of sequential streaming on auditory masking using psychoacoustics and auditory evoked potentials

“…Other within-channel processes are based on the excitation produced by the flanking band at the signal frequency. One possible cue is a change in the modulation depth of the beating masker components due to the presence of the signal (Piechowiak et al, 2007;Klink et al, 2010). As another possible process, Buschermöhle et al (2007) proposed that differences in signal detectability for the different masking conditions may be accounted for by the compression at the output of the auditory filter.…”