Toleration of Background Noises

Abstract

One of the frequently quoted reasons for the rejection of hearing aids is amplification of background noise. The relationship between hearing aid use and toleration of background noise was assessed. Four groups of elderly subjects (at least 65 years old) and one group of young subjects with normal hearing participated in the study. Each group consisted of 15 subjects. The young subjects and elderly subjects in one group with relatively good hearing were tested for comparison with the hearing-impaired subjects. Elderly subjects in the three remaining groups had acquired hearing losses and had been fitted with hearing aids. The subjects were assigned to three groups on the basis of hearing aid use: full-time users, part-time users, and nonusers. The amount of background noise tolerated when listening to speech was tested. The speech stimulus was a story read by a woman and set at an individually chosen most comfortable level. The maskers were a babble of voices, speech-spectrum noise, traffic noise, music, and the noise of a pneumatic drill. There was a significant interaction between groups and noises. The full-time users tolerated significantly higher levels of music and speech-spectrum noise than part-time users and nonusers. In addition, the full-time users, but not the part-time users, assessed themselves as less handicapped in everyday functions when they wore hearing aids than when they did not wear their hearing aids

Comparison of Acceptable Noise Level Generated Using Different Transducers and Response Modes

“…The ANL tests assess the subject's ability to accept noise, and the researchers speculate that acceptance of noise may be an intrinsic property of an individual [1]. The loci of control and self-control seem to influence acceptable noise levels [23].…”

“…The acceptable noise level (ANL) test was developed to quantify the critical amount of background noise that subjects could accept while listening to speech [1–6]. ANL is defined as the lowest signal-to-noise ratio (SNR) that a subject could accept when the target speech was presented at the most comfortable listening level (MCL) [6, 7].…”

“…According to Nabelek et al [8], subjects with an ANL below 7 dB are likely to become successful full-time hearing aid users, while subjects with an ANL above 13 dB are likely to become unsuccessful hearing aids users occasionally or not at all. Previous studies have shown that there is a large variation in ANL across normal-hearing subjects [1, 7, 9–13]. This variation seems unrelated to age [1, 11], gender [14], middle-ear function [15], hearing sensitivity [1, 7, 9, 15, 16], outer hair cell function [15], and efferent pathways utilizing the medial olivocochlear bundle [15].…”

“…In most studies, the sound signal was presented in the sound field through a loudspeaker [18]. However, some studies presented the signals used to measure ANL through an earphone [1]. Olsen and Brännström [17] indicated that the values of ANL obtained from an earphone or loudspeaker may be different.…”

“…In most ANL tests, the subject signals the experimenter to adjust the sound volume. However, Nabelek et al [1] directed subjects to adjust the levels by themselves with visual feedback from the audiometer. The main difference between self-adjusted and audiologist-adjusted measurements is the method to determine the MCL and BNL intensity.…”