Neural Decoding of the Speech Envelope: Effects of Intelligibility and Spectral Degradation

Trends in Hearing, Год журнала: 2024, Номер 28

Опубликована: Янв. 1, 2024

During continuous speech perception, endogenous neural activity becomes time-locked to acoustic stimulus features, such as the amplitude envelope. This speech–brain coupling can be decoded using non-invasive brain imaging techniques, including electroencephalography (EEG). Neural decoding may provide clinical use an objective measure of encoding by brain—for example during cochlear implant listening, wherein signal is severely spectrally degraded. Yet, interplay between and linguistic factors lead top-down modulation thereby complicating audiological applications. To address this ambiguity, we assess envelope under spectral degradation with EEG in acoustically hearing listeners ( n = 38; 18–35 years old) vocoded speech. We dissociate sensory from higher-order processing employing intelligible (English) non-intelligible (Dutch) stimuli, auditory attention sustained a repeated-phrase detection task. Subject-specific group decoders were trained reconstruct held-out data, decoder significance determined via random permutation testing. Whereas reconstruction did not vary resolution, was associated better accuracy general. Results similar across subject-specific analyses, less consistent effects decoding. Permutation tests revealed possible differences statistical experimental condition. In general, while robust observed at individual level, variability within participants would most likely prevent differentiate levels intelligibility on basis.

Язык: Английский

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Neural Tracking Measures of Speech Intelligibility: Manipulating Intelligibility while Keeping Acoustics Unchanged

bioRxiv (Cold Spring Harbor Laboratory), Год журнала: 2023, Номер unknown

Опубликована: Май 18, 2023

Neural speech tracking has advanced our understanding of how brains rapidly map an acoustic signal onto linguistic representations and ultimately meaning. It remains unclear, however, intelligibility is related to the corresponding neural responses. Many studies addressing this question vary level by manipulating waveform, but makes it difficult cleanly disentangle effects from underlying acoustical confounds. Here, using magnetoencephalography (MEG) recordings, we study measures while keeping acoustics strictly unchanged. Acoustically identical degraded stimuli (three-band noise vocoded, ~20 s duration) are presented twice, second presentation preceded original (non-degraded) version speech. This intermediate priming, which generates a 'pop-out' percept, substantially improves passage. We investigate structure affects multivariate Temporal Response Functions (mTRFs). As expected, behavioral results confirm that perceived clarity improved priming. TRF analysis reveals auditory (speech envelope onset) not affected only (bottom-up driven). Critically, findings suggest segmentation sounds into words emerges with better intelligibility, most strongly at later (~400 ms latency) word processing stage, in prefrontal cortex (PFC), line engagement top-down mechanisms associated Taken together, show may provide some objective comprehension.

Язык: Английский

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Neural decoding of the speech envelope: Effects of intelligibility and spectral degradation

bioRxiv (Cold Spring Harbor Laboratory), Год журнала: 2024, Номер unknown

Опубликована: Фев. 23, 2024

During continuous speech perception, endogenous neural activity becomes time-locked to acoustic stimulus features, such as the amplitude envelope. This speech-brain coupling can be decoded using non-invasive brain imaging techniques, including electroencephalography (EEG). Neural decoding may provide clinical use an objective measure of encoding by - for example during cochlear implant (CI) listening, wherein signal is severely spectrally degraded. Yet, interplay between and linguistic factors lead top-down modulation thereby complicating audiological applications. To address this ambiguity, we assess envelope under spectral degradation with EEG in acoustically hearing listeners (n = 38; 18-35 years old) vocoded speech. We dissociate sensory from higher-order processing employing intelligible (English) non-intelligible (Dutch) stimuli, auditory attention sustained a repeated-phrase detection task. Subject-specific group decoders were trained reconstruct held-out data, decoder significance determined via random permutation testing. Whereas reconstruction did not vary resolution, was associated better accuracy general. Results similar across subject-specific analyses, less consistent effects decoding. Permutation tests revealed possible differences statistical experimental condition. In general, while robust observed at individual level, variability within participants would most likely prevent differentiate levels intelligibility on basis.

Язык: Английский

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Neural tracking of the speech envelope predicts binaural unmasking

bioRxiv (Cold Spring Harbor Laboratory), Год журнала: 2024, Номер unknown

Опубликована: Май 22, 2024

Abstract Binaural unmasking is the remarkable phenomenon that it substantially easier to detect a signal in noise, when interaural parameters of are different from those noise – mechanism comes handy so-called cocktail party scenarios. In this study, we investigated effect binaural on neural tracking speech envelope. We measured EEG 8 participants who listened at fixed signal-to-noise ratio (−12 dB or −9 dB, depending material), two conditions: one where and had same phase difference (both having an opposite waveform across ears, SπNπ ), was (only SπN 0). clear benefit behavioral understanding scores, accompanied with increased Moreover, analyzing temporal response functions revealed also resulted decreased peak latencies amplitudes. Our results consistent previous research using auditory evoked potentials steady-state responses quantify cortical levels. they confirm modulated by understanding, even if acoustic kept constant. Significance Statement important contributing factor noisy environments. This first time objectively EEG. From clinical perspective, these could enable evalu-ation mechanisms populations for whom measures difficult obtain, such as young children people cognitive impair-ment. has shown many pathologies (e.g., asymmetric hearing loss, neuropathy, age-related deficits) more sensitive tests contain processing component. paradigm detection objective approach speech.

Язык: Английский

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Neural Dynamics in Speech Processing: Properties, Specificity and Open Questions

Опубликована: Ноя. 22, 2022

Human speech is a particularly relevant acoustic stimulus for our species, due to its role of information transmission during communication. Speech inherently dynamic signal, and recent line research focused on neural activity following the temporal structure speech. We review findings that characterise dynamics in processing compare them with aspects human highlight properties constraints both have, suggesting auditory systems are optimised process then discuss speech-specificity their potential mechanistic origins, summarise open questions field.

Язык: Английский

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