Effect of Reverberation on Acceptable Noise Level in Individuals with Normal Hearing and Hearing Impairment

Abstract

In the present study, the effect of changes in reverberation time on acceptable noise level in individuals with normal hearing and hearing impairment was investigated. The speech material for establishing acceptable noise level were digitally modified to create four reverberation conditions by applying different values of reverberation time (RT} 10 a non-reverberant condition (RT: 0, 0.4, 1.2, and 2 seconds). Two groups of 15 participants each (18-50 years) participated in the study; Group 1 had individuals with normal hearing, and Group II had individuals with bilateral mild- moderately severe hearing impairment, who had no previous experience with any amplification devices. Most comfortable listening level and background noise level measurements were established in each reverberant condition, and from these measurements, acceptable noise levels (AN Ls) were calculated. In individuals with normal hearing, significant difference was found between ANL for non-reverberant stimuli and that for stimuli with RT of 2 seconds. This can be attributed to the unfavorable influence of reverberation on the primary talker; which might have interfered with the listeners ' willingness to accept background noise. The ANLs of participants with normal hearing were better than aided and unaided ANLs of those with sensorineural hearing toss indicating the adverse effect of reverberation and noise on ANLs in participants with hearing impairment. The aided and unaided ANLs were significantly different, with a better value for aided ANL. This is clinically relevant as ANLs can be used to predict success with hearing aid.