The categorical neural organization of speech aids its perception in noise

Bidelman, Gavin M.; Bush, Lauren; Boudreaux, Alex M.

doi:10.1101/652842

Cited by 2 publications

(5 citation statements)

References 74 publications

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“…We propose that categorical coding (i.e., speech with an unambiguous identity) helps partially counteract the negative effects of noise on perception, but only to the extent that speech signals are not too severely degraded. Our findings converge with notions that the process of categorization aids the extraction of speech from noise whereby abstract categories help fortify the speech code and make it more resistant to external noise interference (e.g., Helie, 2017;Bidelman et al, 2019b).…”

Section: Discussionsupporting

confidence: 85%

“…EEG was also recorded during the categorization task. These data are reported elsewhere (Bidelman et al, 2019b).…”

Section: Speech Stimuli and Behavioral Tasksupporting

confidence: 75%

“…Moreover, both our behavioral and physiological data indicated more categorical responses to unambiguous relative to ambiguous tokens at intermediate noise levels. Thus, noise-related decrements in our data likely reflect fuzzier matches between speech signals and templates of speech sounds (Bidelman et al, 2019b).…”

Section: Discussionmentioning

confidence: 82%

“…Neuroimaging data indicates that the brain processes competing sound streams within the same neural pathways, but devotes more attention to the target stream (Evans et al, 2016). Our recent electrophysiological study found that neural activity was not only stronger for category (unambiguous) relative to non-category (ambiguous) speech sounds but the former was more invariant to noise interference, suggesting CP promotes robust speech perception by "sharpening" category members in noisy feature space (Bidelman et al, 2019b).…”

Section: Introductionmentioning

confidence: 85%

“…Categorization accuracy and speed deteriorate with noise interference by remains possible until severely degraded SNRs. Data reproduced fromBidelman et al (2019b). Spectrogram reproduced fromBidelman et al (2014), with permission from John Wiley & Sons.…”

mentioning

confidence: 99%

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Autonomic Nervous System Correlates of Speech Categorization Revealed Through Pupillometry

Lewis

Bidelman

2020

Front. Neurosci.

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Human perception requires the many-to-one mapping between continuous sensory elements and discrete categorical representations. This grouping operation underlies the phenomenon of categorical perception (CP)-the experience of perceiving discrete categories rather than gradual variations in signal input. Speech perception requires CP because acoustic cues do not share constant relations with perceptual-phonetic representations. Beyond facilitating perception of unmasked speech, we reasoned CP might also aid the extraction of target speech percepts from interfering sound sources (i.e., noise) by generating additional perceptual constancy and reducing listening effort. Specifically, we investigated how noise interference impacts cognitive load and perceptual identification of unambiguous (i.e., categorical) vs. ambiguous stimuli. Listeners classified a speech vowel continuum (/u/-/a/) at various signal-tonoise ratios (SNRs [unmasked, 0 and −5 dB]). Continuous recordings of pupil dilation measured processing effort, with larger, later dilations reflecting increased listening demand. Critical comparisons were between time-locked changes in eye data in response to unambiguous (i.e., continuum endpoints) tokens vs. ambiguous tokens (i.e., continuum midpoint). Unmasked speech elicited faster responses and sharper psychometric functions, which steadily declined in noise. Noise increased pupil dilation across stimulus conditions, but not straightforwardly. Noise-masked speech modulated peak pupil size (i.e., [0 and −5 dB] > unmasked). In contrast, peak dilation latency varied with both token and SNR. Interestingly, categorical tokens elicited earlier pupil dilation relative to ambiguous tokens. Our pupillary data suggest CP reconstructs auditory percepts under challenging listening conditions through interactions between stimulus salience and listeners' internalized effort and/or arousal.

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Section: Discussionsupporting

confidence: 85%

“…EEG was also recorded during the categorization task. These data are reported elsewhere (Bidelman et al, 2019b).…”

Section: Speech Stimuli and Behavioral Tasksupporting

confidence: 75%

Section: Discussionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 85%

mentioning

confidence: 99%

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Autonomic Nervous System Correlates of Speech Categorization Revealed Through Pupillometry

Lewis

Bidelman

2020

Front. Neurosci.

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Plasticity in auditory categorization is supported by differential engagement of the auditory-linguistic network

Bidelman

Walker

2019

Preprint

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To construct our perceptual world, the brain categorizes variable sensory cues into behaviorally-relevant groupings. Categorical representations are apparent within a distributed fronto-temporo-parietal brain network but how this neural circuitry is shaped by experience remains undefined. Here, we asked whether speech (and music) categories might be formed within different auditory-linguistic brain regions depending on listeners’ auditory expertise. We recorded EEG in highly skilled (musicians) vs. novice (nonmusicians) perceivers as they rapidly categorized speech and musical sounds. Musicians showed perceptual enhancements across domains, yet source EEG data revealed a double dissociation in the neurobiological mechanisms supporting categorization between groups. Whereas musicians coded categories in primary auditory cortex (PAC), nonmusicians recruited non-auditory regions (e.g., inferior frontal gyrus, IFG) to generate category-level information. Functional connectivity confirmed nonmusicians’ increased left IFG involvement reflects stronger routing of signal from PAC directed to IFG, presumably because sensory coding is insufficient to construct categories in less experienced listeners. Our findings establish auditory experience modulates specific engagement and inter-regional communication in the auditory-linguistic network supporting CP. Whereas early canonical PAC representations are sufficient to generate categories in highly trained ears, less experienced perceivers broadcast information downstream to higher-order linguistic brain areas (IFG) to construct abstract sound labels.

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The categorical neural organization of speech aids its perception in noise

Cited by 2 publications

References 74 publications

Autonomic Nervous System Correlates of Speech Categorization Revealed Through Pupillometry

Autonomic Nervous System Correlates of Speech Categorization Revealed Through Pupillometry

Plasticity in auditory categorization is supported by differential engagement of the auditory-linguistic network

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