Auditory Steady-State Responses and the Effects of Interaural Decoherence and Presence of Vision

The Auditory Steady-State Response (ASSR) is a periodic neural response used to detect speech and hearing loss, and it is also used as a Brain-Computer Interface paradigm. Our paper identifies two key factors that impact the quality and consistency of the ASSR. First is the interaural decoherence, the timing and intensity of sounds arriving at two ears produced by speakers in reverberant environments. Second is the impact of vision on modulating auditory perception and spatial attention, which could potentially influence the neural synchronisation of the response. To demonstrate this, we conducted an experiment on 26 healthy participants to examine the effects of interaural decoherence, by comparing the frequency responses between speakers and earphones, and the presence of vision, by comparing being blindfolded and non-blindfolded, on the ASSR. This study demonstrates that earphones elicit more consistent and reliable ASSRs compared to speakers, emphasising the detrimental effects of interaural decoherence from speaker-based sound delivery on ASSRs. Furthermore, we found that the response is more biased to one side in the absence of vision compared to the presence of vision. This study highlights the importance of using rooms with anechoic properties or less reverberation when using speakers to ensure the consistency and clarity of the response. Future ASSR paradigms should also consider fixating on a target to elicit less bias in ASSR and more accurate spatial features.