No change in the acoustic reflex threshold and auditory brainstem response following short-term acoustic stimulation in normal hearing adults

Abstract

22Unilateral auditory deprivation or stimulation can induce changes in loudness and modify the 23 sound level required to elicit the acoustic reflex. This has been explained in terms of a change 24 in neural response, or gain, for a given sound level. However, it is unclear if these changes 25 are driven by the asymmetry in auditory input or if they will also occur following bilateral 26 changes in auditory input. The present study used a cross-over trial of unilateral and bilateral 27 amplification to investigate changes in the acoustic reflex thresholds (ARTs) and the auditory 28 brainstem response (ABR) in normal hearing listeners. Each treatment lasted 7 days and there 29 was a 7-day washout period between the treatments. There was no significant change in the 30 ART or ABR with either treatment. This null finding may have occurred because the 31 amplification was insufficient to induce experience-related changes to the ABR and ART. 32Based on the null findings from the present study, and evidence of a change in ART in 33 previous unilateral hearing aid use in normal hearing listeners, the threshold to trigger 34 adaptive changes appears to be around 5 days of amplification with real ear insertion gain 35 greater than 13-17 dB.