Hearing loss is associated with delayed neural responses to continuous speech

Kries

Vandermosten

et al. 2022

Preprint

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Background: Older adults process speech differently, but it is not yet clear how aging affects different levels of processing natural, continuous speech, both in terms of bottom-up acoustic analysis and top-down generation of linguistic-based predictions. We studied natural speech processing across the adult lifespan via EEG measurements of neural tracking. Goals: Our goals are to analyze the unique contribution of linguistic speech processing across the adult lifespan using natural speech, while controlling for the influence of acoustic processing. In particular, we focus on changes in spatial and temporal activation patterns in response to natural speech across the lifespan. Methods: 52 normal-hearing adults between 17 and 82 years of age listened to a naturally spoken story while the EEG signal was recorded. We investigated the effect of age on acoustic and linguistic processing of speech. Because age correlated with hearing capacity and measures of cognition, we investigated whether the observed age effect is mediated by these factors. Furthermore, we investigated whether there is an effect of age on hemisphere lateralization and on spatiotemporal patterns of the neural responses. Results: Our EEG results showed that linguistic speech processing declines with advancing age. Moreover, as age increased, the neural response latency to certain aspects of linguistic speech processing increased. Also acoustic neural tracking decreased with increasing age but in contrast to linguistic processing, older subjects showed shorter latencies for early acoustic responses to speech. No evidence was found for hemispheric lateralization in neither younger nor older adults during linguistic speech processing. Most of the observed aging effects on acoustic and linguistic processing were not explained by age-related decline in hearing capacity or cognition. However, our results suggest that the effect of increasing neural response latency with age for word-level linguistic processing is likely more due to an age-related decline in cognition than a robust effect of age. Conclusion: Spatial and temporal characteristics of the neural responses to continuous speech change across the adult lifespan for both acoustic and linguistic speech processing. These are most likely explained by compensation mechanisms that occur during healthy aging. Traces of this compensation mechanism are reported as modifications in the neural response to acoustic and linguistic speech characteristics in terms of spatial and temporal differences, suggesting structural and functional changes. Additionally, different frontal patterns were observed for linguistic processing, suggesting that older adults recruit additional frontal brain regions to compensate for the age-related decline.

Section: Current Studysupporting

confidence: 91%

Neural tracking of linguistic speech representations decreases with advancing age

Kries

Vandermosten

et al. 2022

Preprint

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“…Increased latencies are often observed in more complex conditions with a higher task demand, like for example lower stimulus intensity, vocoded speech or speech in noise (Mirkovic et al, 2019; Verschueren et al, 2021; Kraus et al, 2020). The latency of the neural responses can also be related to neural processing efficiency (Bidelman et al, 2019; Gillis et al, 2021a). In more detail, a larger latency indicates that more processing time is required to process the same speech characteristics, showing reduced neural processing efficiency.…”

Section: Discussionmentioning

confidence: 99%

Speech understanding oppositely affects acoustic and linguistic neural tracking in a speech rate manipulation paradigm

Verschueren

Vanthornhout

et al. 2022

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When listening to continuous speech, the human brain can track features of the presented speech signal. It has been shown that neural tracking of acoustic features is a prerequisite for speech understanding and can predict speech understanding in controlled circumstances. However, the brain also tracks linguistic features of speech, which may be more directly related to speech understanding. We investigated acoustic and linguistic speech processing as a function of varying speech understanding by manipulating the speech rate. In this paradigm, acoustic and linguistic speech processing are affected simultaneously but in opposite directions: When the speech rate increases, more acoustic information per second is present. In contrast, linguistic information decreases as speech becomes less intelligible at higher speech rates. We measured the EEG of 18 participants who listened to speech at various speech rates. As expected and confirmed by the behavioral results, speech understanding decreased with increasing speech rate. Accordingly, linguistic neural tracking decreased with increasing speech rate, but acoustic neural tracking increased. This indicates that neural tracking of linguistic representations can capture the gradual effect of decreasing speech understanding. In addition, increased acoustic neural tracking does not necessarily imply better speech understanding. This suggests that, although more challenging to measure due to the low signal-to-noise ratio, linguistic neural tracking may be a more direct predictor of speech understanding.

“…Similarly, Decruy et al (2020b) and Fuglsang et al (2020) found increased envelope tracking for hearing-impaired listeners compared to age-matched normal-hearing listeners. The enhanced tracking in older listeners or listeners with a hearing impairment may be explained by a compensatory central gain mechanism (Parthasarathy et al, 2019; De Villers-Sidani et al, 2010; Chambers et al, 2016), recruitment of additional cortical resources (Brodbeck et al, 2018b; Gillis et al, 2021a) and increased listening effort and attention (Decruy et al, 2020a; Vanthornhout et al, 2019; Lesenfants and Francart, 2020). With an innovative artefact removal technique, Somers et al (2019) succeeded to analyse envelope tracking for cochlear implant listeners as well.…”

Section: Neural Tracking Of the Speech Envelopementioning

confidence: 99%

Neural tracking as a diagnostic tool to assess the auditory pathway

Canneyt

Vanthornhout

et al. 2021

Preprint

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The neural tracking framework enables the analysis of neural responses (EEG) to continuous natural speech, e.g., a story or a podcast. This allows for objective investigation of a range of auditory and linguistic processes in the brain during natural speech perception. This approach is more ecologically valid than traditional auditory evoked responses and has great potential for both research and clinical applications. In this article, we review the neural tracking framework and highlight three prominent examples of neural tracking analyses. This includes the neural tracking of the fundamental frequency of the voice (f0), the speech envelope and linguistic features. Each of these analyses provides a unique point of view into the hierarchical stages of speech processing in the human brain. f0-tracking assesses the encoding of fine temporal information in the early stages of the auditory pathway, i.e. from the auditory periphery up to early processing in the primary auditory cortex. This fundamental processing in (mostly) subcortical stages forms the foundation of speech perception in the cortex. Envelope tracking reflects bottom-up and top-down speech-related processes in the auditory cortex, and is likely necessary but not sufficient for speech intelligibility. To study neural processes more directly related to speech intelligibility, neural tracking of linguistic features can be used. This analysis focuses on the encoding of linguistic features (e.g. word or phoneme surprisal) in the brain. Together these analyses form a multi-faceted and time-effective objective assessment of the auditory and linguistic processing of an individual.