Slide Slam F7
Comprehension-relevant speech tracking in the auditory cortex and beyond
Anne Keitel1; 1University of Dundee
Cortical tracking of continuous speech is a ubiquitous process that can be seen across different timescales and across many different brain areas. Less comprehensible speech is generally associated with weaker tracking, but the exact contributions of tracking at different linguistic timescales (words, syllables, etc) and in different areas remain elusive. I will first present evidence showing that it makes sense to differentiate between “general tracking” and tracking that influences our comprehension. Here, we used a single-trial approach to measure individual speech-in-noise comprehension of sentences. We found that the auditory cortex tracks speech faithfully at all timescales, but this does not necessarily influence our comprehension. Comprehension was only predicted by tracking in higher-level mid-temporal areas at the word rate, and motor areas at the phrase rate, respectively. This likely depended on the used behavioural task. The idea that not all low-level representations are behaviourally relevant is also supported by a decoding study on auditory and visual speech (lip reading) comprehension. Here we showed that speech representations were overall widespread, but that those few regions that showed comprehension-relevant representations of speech were relatively distinct for auditory and visual modalities. Extending this idea of general vs behaviourally-relevant tracking to music, I will also show that tracking in frontal areas predicts beat perception (finger-tapping performance), whereas tracking in putative low-level auditory areas does not. Taken together, these findings demonstrate that it is useful to include a behavioural task when analysing speech (and music) tracking, to disentangle general processes and those that predict behaviour and comprehension in a given task.