Detecting and representing predictable structure during auditory scene analysis.

Ediz Sohoglu,Maria Chait

doi:10.7554/elife.19113

Abstract

We use psychophysics and MEG to test how sensitivity to input statistics facilitates auditory-scene-analysis (ASA). Human subjects listened to 'scenes' comprised of concurrent tone-pip streams (sources). On occasional trials a new source appeared partway. Listeners were more accurate and quicker to detect source appearance in scenes comprised of temporally-regular (REG), rather than random (RAND), sources. MEG in passive listeners and those actively detecting appearance events revealed increased sustained activity in auditory and parietal cortex in REG relative to RAND scenes, emerging ~400 ms of scene-onset. Over and above this, appearance in REG scenes was associated with increased responses relative to RAND scenes. The effect of temporal structure on appearance-evoked responses was delayed when listeners were focused on the scenes relative to when listening passively, consistent with the notion that attention reduces 'surprise'. Overall, the results implicate a mechanism that tracks predictability of multiple concurrent sources to facilitate active and passive ASA.

Highlights

Natural scenes are highly structured, containing statistical regularities in both space and time and over multiple scales (Julesz, 1981; Portilla and Simoncelli, 2000; Geisler, 2008; McDermott et al, 2013; Theunissen and Elie, 2014)
Our results provide evidence in support of precision accounts: we show that brain responses to ongoing acoustic scenes, and to new sources appearing within those scenes, increase in the presence of regular statistical structure
Temporally regular scenes are associated with enhanced detection performance and in a manner independent of the temporal structure of the appearing source

Summary

Introduction

Natural scenes are highly structured, containing statistical regularities in both space and time and over multiple scales (Julesz, 1981; Portilla and Simoncelli, 2000; Geisler, 2008; McDermott et al, 2013; Theunissen and Elie, 2014). A growing body of work suggests that the human brain is sensitive to this statistical structure (Rao and Ballard, 1999; Naatanen et al, 2001; Bar, 2004; Oliva and Torralba, 2007; Costa-Faidella et al, 2011; Garrido et al, 2013; Okazawa et al, 2015; Barascud et al, 2016) and uses it for efficient scene analysis (Winkler et al, 2009; Andreou et al, 2011; Bendixen, 2014). The present work addresses both of these issues in the context of an auditory scene

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Conclusion