Auditory cortex is susceptible to lexical influence as revealed by informational vs. energetic masking of speech categorization

Carter, Jared A.; Bidelman, Gavin M.

doi:10.1101/2020.10.20.347724

Cited by 3 publications

(12 citation statements)

References 69 publications

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“…In contrast, un-ordered speech presented back-to-back would not load such operations and thus may explain the reduced rMFG activity for random presentation. The simultaneous activation of canonical auditory areas (STG) concurrent with these two frontal regions leads us to infer that while auditory cortex is sensitive to category structure (present study; 7,39 ), top-down modulations from frontal lobes dynamically shapes category percepts online during speech perception.…”

Section: Electrophysiological Correlates Of Perceptual Warpingmentioning

confidence: 84%

“…Beyond its established role in speech-language processing, left IFG is heavily involved in category decisions, particularly under states of stimulus uncertainty (i.e., randomness, noise) 7,30,39 . Related, we find direction-related modulations in the perceptual warping of speech categories (to an otherwise identical sound) are predicted by left IFG engagement.…”

Section: Electrophysiological Correlates Of Perceptual Warpingmentioning

confidence: 99%

“…The copyright holder for this preprint this version posted December 9, 2021. ; https://doi.org/10.1101/2021.12.07.470603 doi: bioRxiv preprint speech CP 4,5,7 , we hypothesized (1) the location of listeners' perceptual boundary would shift according to the direction of stimulus presentation and (2) perceptual warping would be accompanied by late modulations in the ERPs.…”

Section: Introductionmentioning

confidence: 99%

“…On one hand, categories might arise due to innate psychophysiological constraints 3 . Alternatively, there is ample evidence that top-down processing influences speech categorization as suggested by enhancements observed in highly proficient listeners 4-7 and biasing effects, when individuals hear a different category depending on the surrounding speech context 8 .…”

Section: Introductionmentioning

confidence: 99%

“…We measured behavioral and multichannel EEG responses during rapid phoneme identification tasks where tokens along an identical continuum were presented in random vs. serial (forward or backward) order. Based on previous studies examining nonlinear dynamics 9,10 and top-down influences in speech CP 4,5,7 , we hypothesized (1) the location of listeners’ perceptual boundary would shift according to the direction of stimulus presentation and (2) perceptual warping would be accompanied by late modulations in the ERPs.…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear dynamics in auditory cortical activity reveal the neural basis of perceptual warping in speech categorization

Carter

Buder

Bidelman

2021

Preprint

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Surrounding context influences speech listening, resulting in dynamic shifts to category percepts. To examine its neural basis, event-related potentials (ERPs) were recorded during vowel identification with continua presented in random, forward, and backward orders to induce perceptual nonlinearities. Behaviorally, sequential order shifted listeners' categorical boundary vs. random delivery revealing perceptual warping (biasing) of the heard phonetic category dependent on recent stimulus history. ERPs revealed later (~300 ms) activity localized to superior temporal and middle/inferior frontal gyri that predicted listeners' hysteresis magnitudes. Findings demonstrate that top-down, stimulus history effects on speech categorization are governed by interactions between frontotemporal brain regions.

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Section: Electrophysiological Correlates Of Perceptual Warpingmentioning

confidence: 84%

Section: Electrophysiological Correlates Of Perceptual Warpingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Nonlinear dynamics in auditory cortical activity reveal the neural basis of perceptual warping in speech categorization

Carter

Buder

Bidelman

2021

Preprint

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Perceptual warping exposes categorical representations for speech in human brainstem responses

Carter

Bidelman

2022

Preprint

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The brain transforms continuous acoustic events into discrete category representations to downsample the speech signal for our perceptual-cognitive systems. Such phonetic categories are highly malleable and heir percepts can change depending on surrounding stimulus context. Previous work suggests these acoustic-phonetic mapping and perceptual warping of speech emerge in the brain no earlier than auditory cortex. Here, we examined whether these auditory-category phenomena inherent to speech perception occur even earlier in the human brain, at the level of auditory brainstem. We recorded speech-evoked frequency following responses (FFRs) during a task designed to induce more/less warping of listeners' perceptual categories depending on stimulus presentation order of a speech continuum (random, forward, backward directions). We used a novel clustered stimulus paradigm to rapidly record the high trial counts needed for FFRs concurrent with active behavioral tasks. We found serial stimulus order caused perceptual shifts (hysteresis) near listeners' category boundary confirming identical speech tokens are perceived differentially depending on stimulus context. Critically, we further show neural FFRs during active (but not passive) listening are enhanced for prototypical vs. category-ambiguous tokens and are biased in the direction of listeners' phonetic label even for acoustically-identical speech stimuli. Our data expose FFRs carry category-level information and suggest top-down processing actively shapes the neural encoding and categorization of speech at subcortical levels. These findings suggest the acoustic-phonetic mapping and perceptual warping in speech perception occur surprisingly early along the auditory neuroaxis, which might aid understanding by reducing ambiguity inherent to the speech signal.

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Functional benefits of continuous vs. categorical listening strategies on the neural encoding and perception of noise-degraded speech

Rizzi,

Bidelman

2024

Preprint

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Acoustic information in speech changes continuously, yet listeners form discrete perceptual categories to ease the demands of perception. Being a more continuous/gradient as opposed to a discrete/categorical listener may be further advantageous for understanding speech in noise by increasing perceptual flexibility and resolving ambiguity. The degree to which a listener's responses to a continuum of speech sounds are categorical versus continuous can be quantified using visual analog scaling (VAS) during speech labeling tasks. Here, we recorded event-related brain potentials (ERPs) to vowels along an acoustic-phonetic continuum (/u/ to /a/) while listeners categorized phonemes in both clean and noise conditions. Behavior was assessed using standard two alternative forced choice (2AFC) and VAS paradigms to evaluate categorization under task structures that promote discrete (2AFC) vs. continuous (VAS) hearing, respectively. Behaviorally, identification curves were steeper under 2AFC vs. VAS categorization but were relatively immune to noise, suggesting robust access to abstract, phonetic categories even under signal degradation. Behavioral slopes were positively correlated with listeners' QuickSIN scores, suggesting a behavioral advantage for speech in noise comprehension conferred by gradient listening strategy. At the neural level, electrode level data revealed P2 peak amplitudes of the ERPs were modulated by task and noise; responses were larger under VAS vs. 2AFC categorization and showed larger noise-related delay in latency in the VAS vs. 2AFC condition. More gradient responders also had smaller shifts in ERP latency with noise, suggesting their neural encoding of speech was more resilient to noise degradation. Interestingly, source-resolved ERPs showed that more gradient listening was also correlated with stronger neural responses in left superior temporal gyrus. Our results demonstrate that listening strategy (i.e., being a discrete vs. continuous listener) modulates the categorical organization of speech and behavioral success, with continuous/gradient listening being more advantageous to speech in noise perception.

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Auditory cortex is susceptible to lexical influence as revealed by informational vs. energetic masking of speech categorization

Cited by 3 publications

References 69 publications

Nonlinear dynamics in auditory cortical activity reveal the neural basis of perceptual warping in speech categorization

Nonlinear dynamics in auditory cortical activity reveal the neural basis of perceptual warping in speech categorization

Perceptual warping exposes categorical representations for speech in human brainstem responses

Functional benefits of continuous vs. categorical listening strategies on the neural encoding and perception of noise-degraded speech

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