The Auditory Brainstem Response and Envelope Following Response: Investigating Within-Subject Variation to Stimulus Polarity

Though the envelope following response (EFR) has potential to become an effective tool for hearing aid validation, studies have observed a considerable degree of within-subject variation with stimulus polarity that could affect its clinical usefulness. This study investigated whether a relationship exists between the polarity-sensitive variation observed in EFR amplitude and that observed in the latencies of a related neural response, the auditory brainstem response (ABR). Low frequency masked clicks and the dual-f0 stimulus /susaʃi/ were used to evoke alternating polarity ABRs and EFRs, respectively, in 31 normal hearing adults. Maximum and median differences between polarity conditions were calculated. A significant correlation was found between median absolute differences in EFR amplitude and ABR latency, indicating the polarity-sensitive variation may arise from common sources in the auditory pathway when low frequency stimuli are used. Future studies should employ imaging techniques to further explore the relationship between the EFR and ABR