Induced Alpha And Beta Electroencephalographic Rhythms Covary With Single-Trial Speech Intelligibility In Competition

Abstract

Neurophysiological studies suggest that intrinsic brain oscillations influence sensory processing, especially of rhythmic stimuli like speech. Prior work suggests that brain rhythms may mediate perceptual grouping and selective attention to speech amidst competing sound, as well as more linguistic aspects of speech processing like predictive coding. However, we know of no prior studies that have directly tested, at the single-trial level, whether brain oscillations relate to speech-in-noise outcomes. Here, we combined electroencephalography while simultaneously measuring intelligibility of spoken sentences amidst two different interfering sounds: multi-talker babble or speech-shaped noise. We find that induced parieto-occipital alpha (7-15 Hz; thought to modulate attentional focus) and frontal beta (13-30 Hz; associated with speech-motor predictive coding) oscillations covary with trial-wise percent-correct scores; importantly, alpha and beta power provide significant independent contributions to predicting single-trial behavioral outcomes. Moreover, we observed large individual differences in the across-trial distribution of alpha and beta power as well as in the alpha-to-beta power ratio. This raises the possibility that listeners employed different task strategies: some may have relied heavily on focusing attention, while others on predictive coding. These results can inform models of speech processing and guide noninvasive measures to index different neural processes that together support complex listening.

Assessing attentional task-related electroencephalogram signal variations by using mobile electroencephalogram technology: An experimental study

“…Parieto-occipital alpha (7–15 Hz; thought to modulate attentional focus) and frontal beta (13–30 Hz; associated with maintenance of the current sensorimotor state and predictive coding) oscillations covary with trial-wise percent-correct scores; importantly, alpha and beta power provide significant independent contributions to predicting single-trial behavioral outcomes. [30] In this study, the delta waves were related to the whole brain, the alpha and high gamma waves to the left posterior lobe, and the beta and low gamma waves to both frontal lobes. The occurrences of alpha and beta are similar to other reports, while occurrences of delta and gamma suggest these frequency power bands also may be key to predicting attentional functions.…”

Improved coherence measure for EEG-based speech tracking in hearing impaired listeners

“…Two options are considered here. The first has been used in [15] in speech envelope to EEG coherence estimation…”

“…Specifically, there are robust linear relationships between the speech envelope and the concurrent EEG signatures. Hence, spectral November 27, 2023 1/13 coherence analysis between the speech envelope and EEG signals can confidently identify and analyze the underlying system to a significant degree, as demonstrated in [15,16]. Spectral coherence is a measure of the linear coupling between two signals, calculated as the cross-spectrum normalized by the respective auto-spectrum of both signals.…”

Impact of Reduced Spectral Resolution on Temporal-Coherence-Based Source Segregation

“…Manipulating a masker's modulation spectrum to be less similar to that of the target sound reduces modulation masking (masking of target modulations or envelopes in a modulation-frequencyspecific manner) in listeners with normal hearing (Bacon and Grantham, 1989;Stone and Moore, 2014;Viswanathan et al, 2021a). However, both CI users (Nelson et al, 2003;Stickney et al, 2004;Cullington and Zeng, 2008) and hearing-impaired listeners relying on acoustic hearing (Festen and Plomp, 1990;Bacon et al, 1998;Hall et al, 2012) show little to no release from modulation masking when the masker's modulation spectrum is altered to be less like that of the target, an observation that is in line with the possibility that reduced spectral resolution interferes with source segregation.…”

“…According to the temporal-coherence theory of auditory scene analysis, temporally coherent sound modulations help group together sound elements from distinct frequency channels to form a perceptual object, thereby aiding segregation or unmasking of a target sound source from other competing sources (Elhilali et al, 2009;Teki et al, 2013;Viswanathan et al, 2021aViswanathan et al, , 2022. As a consequence, masker components that are temporally coherent with the target but in distinct frequency channels not driven by the target may interfere with target encoding and perception.…”