Artifactual Responses in Auditory Steady State Responses Recorded Using Phase Coherence Method

Abstract

It has been reported that artifacts at high stimulus levels contaminated auditory steady state responses (ASSR) when weighted averaging method was used to detect the responses. A few commercially available instruments use phase coherence method to detect the presence of ASSR. The current study investigated the presence of artifactual responses in ASSR when a phase coherence method is used. ASSR was recorded in fifteen adult participants with profound hearing loss, who did not show any behavioural responses. The upper limits of stimulation for obtaining artifact free ASSR, using supra aural headphones, insert earphones and a bone vibrator were determined. Analysis of the results revealed that the upper limit of stimulation for obtaining artifcat free ASSR is 95 dBHL for supra aural headphones, 105 dBHL for insert ear-phones and 50 dBHL for a bone vibrator. Phase analysis of the artifacts suggested that artifacts were either due to non-auditory physiological responses and/or electromagnetic aliasing artefacts.