How phonetically selective is the human auditory cortex?

doi:10.1016/j.tics.2014.04.001

Trends in Cognitive Sciences

Volume 18, Issue 8, August 2014, Pages 391-392

https://doi.org/10.1016/j.tics.2014.04.001 Get rights and content

Responses in the human auditory cortex to natural speech reveal a dual character. Often they are categorically selective to phonetic elements, serving as a gateway to abstract linguistic representations. But at other times they reflect a distributed generalized spectrotemporal analysis of the acoustic features, as seen in early mammalian auditory cortices.

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Acknowledgments

This work was funded by National Institutes of Health (NIH) grant R01 DC007657 and an Advanced European Research Council (ERC) grant from the EU (295603).

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Cited by (3)

Low-frequency cortical entrainment to speech reflects phoneme-level processing
2015, Current Biology
Citation Excerpt :
Specifically, based on recordings from the superior temporal gyrus (STG) in epilepsy patients, high gamma frequency (75–150 Hz) activity was shown to encode an acoustic-phonetic representation of speech. Based on this, it has been suggested that the STG may be a transitional stage in the auditory processing hierarchy, early enough to still encode the acoustic features of speech but high enough to exhibit response selectivity to complex spectrotemporal patterns [31]. The fact that the ECoG recordings were shown to be optimally sensitive to intermediate acoustic-phonetic speech features at an intermediate response time lag of around 150 ms [8] agrees reasonably well with the increased discriminative power of our EEG responses at this latency.
The human ability to understand speech is underpinned by a hierarchical auditory system whose successive stages process increasingly complex attributes of the acoustic input. It has been suggested that to produce categorical speech perception, this system must elicit consistent neural responses to speech tokens (e.g., phonemes) despite variations in their acoustics. Here, using electroencephalography (EEG), we provide evidence for this categorical phoneme-level speech processing by showing that the relationship between continuous speech and neural activity is best described when that speech is represented using both low-level spectrotemporal information and categorical labeling of phonetic features. Furthermore, the mapping between phonemes and EEG becomes more discriminative for phonetic features at longer latencies, in line with what one might expect from a hierarchical system. Importantly, these effects are not seen for time-reversed speech. These findings may form the basis for future research on natural language processing in specific cohorts of interest and for broader insights into how brains transform acoustic input into meaning.
Phonemes: Lexical access and beyond
2018, Psychonomic Bulletin and Review
Cortical measures of phoneme-level speech encoding correlate with the perceived clarity of natural speech
2018, eNeuro

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Trends in Cognitive Sciences

SpotlightHow phonetically selective is the human auditory cortex?

Section snippets

Acknowledgments

Cognition

Phonetic feature encoding in human superior temporal gyrus

Science

Toward a model for lexical access based on acoustic landmarks and distinctive features

J. Acoust. Soc. Am.

Categories and boundaries in speech and music

Percept. Psychophys.

Representation of the voice onset time (VOT) speech parameter in population responses within primary auditory cortex of the awake monkey

J. Acoust. Soc. Am.

Spotlight
How phonetically selective is the human auditory cortex?