14th Speech in Noise Workshop, 12-13 January 2023, Split, Croatia 14th Speech in Noise Workshop, 12-13 January 2023, Split, Croatia

Feeling the rhythm: Vibrotactile enhancement of speech-in-noise comprehension

Tobias Reichenbach
Imperial College London, UK
FAU Nuremberg-Erlangen, Germany

Pierre Guilleminot
Imperial College London, UK

Background: Natural speech contains intrinsic rhythms set by the rate of phonemes, words and syllables. These rhythms are used by the brain to process speech. Neural activity in the cerebral cortex in the delta and theta frequency bands tracks the sequence of words and syllabes, and the neural tracking is presumably used to parse speech into these different linguistic units for further processing. Modulating the cortical tracking through transcranial alternating current stimulation has indeed been found to influence the comprehension of speech in noise.

Methods: Here we show that vibrotacile stimuli can provide another avenue for modulating the cortical tracking and speech comprehension (Guilleminot and Reichenbach, 2022, doi:10.1073/pnas.2117000119). The somatosensory system indeed innervates the primary auditory cortex and can, in particular, influence its neural activity in the theta band. We therefore investigated how the comprehension of continuous speech in noise may be influenced by the simultaneous presentation of vibrotactile pulses that are linked to the timing of syllables.

Results: We found that, when the timing of the pulses coincided with the perceptual center of the syllabes, speech comprehension was enhanced by about 5% compared to no tactile signals or to a sham stimulation. Timing differences between the tactile pulses and the perceptual center of the syllables led to less speech enhancement or to impediment of speech-in-noise comprehension. EEG recordings revealed that the modulation of speech comprehension through the tactile pulses could be partially explained by neural indices of multisensory integration in the auditory cortex. Another experiment on the recognition of individual syllables showed that vibrotactile pulses can modulate speech comprehension also after the tactile stimulation has occurred, in a manner that is consistent with the hypothesis that the pulses reset the phase of ongoing oscillatory activity in the theta frequency range.

Conclusion: Taken together, our results show how vibrotactile signals can enhance speech comprehension through multisensory integration linked to speech rhythms, and may open up a possible avenue for future multisensory auditory prosthesis.

Last modified 2023-01-06 23:41:06