Feel sounds with your hands: Exploring tactile frequency-following response

Auditory perception is often influence by other senses. Prior studies have documented that the auditory cortex can respond to vibration, but the nature of this neural response remains unclear. The frequency-following response (FFR) is a non-invasive evoked brain response that can be used to study the fidelity of periodicity encoding of complex sounds. The main goal of this study was to investigate if tactile processing of sounds retains periodicity information as measured by the FFR. We acquired electroencephalography while participants were presented with repetitions of a synthesized speech syllable /da/ under three conditions (Auditory, Tactile, and both). A technology developed within our laboratory (Multichannel Vibrotactile Glove) was used to present sounds to all fingers. Results reveal that it is possible to measure a tactile FFR using vibrotactile stimulation, which is similar to the auditory FFR, but exhibits somewhat different characteristics as compared to unimodal auditory FFR, including lower amplitude and no sensitivity to harmonics. These findings suggest that these modalities interact, opening up questions about the origins and pathways responsible for the phenomena and introduces potential uses of tactile perception to mitigate the effect of hearing loss in speech and music perception.