Acceptable noise level: A clinical measure for predicting hearing aid outcome.

stated that we are in the age of outcome measures; these measures are essential in the assessment of hearing aid efficacy. While numerous efforts have been made to predict hearing aid outcome, an accurate method of predicting how people will utilize their hearing aids does not exist. Furthermore, it is not known why some individuals are better hearing aid users than others. The research we have been conducting at the University of Tennessee since 1991 concerns whether utilization of hearing aids can be predicted from measures available before hearing aids are fitted and worn. Background noise is often indicated as a problem for hearing aid users. The effect of background noise is typically assessed in audiology by measuring speech perception scores at fixed signal-to-noise ratios (S/N). Unfortunately, these scores are poor predictors of hearing aid use. We hypothesized that perhaps what troubles hearing aid users is not reduced speech understanding in background noise but the presence of background noise itself. We further hypothesized that willingness to listen to speech in the presence of noise might be more indicative of hearing aid utilization than speech understanding in noise. We decided to measure this willingness as the maximum background noise level (BNL) that an individual is willing to accept when listening to speech presented at the most comfortable listening level (MCL). The difference between MCL and BNL is termed the “acceptable noise level” (ANL) and is expressed in dB. Therefore, an individual who accepts more background noise has a lower ANL than a person who accepts less noise. In our first study on ANL (Nabelek et al, 1991) (then called “tolerated speech-to-noise ratio”), we determined that good hearing aid users accepted significantly more background noise than occasional hearing aid users or persons who stopped using their hearing aids entirely. The findings of the first study with small groups of subjects (15 in each group) encouraged us to study the ANL as a potential measure for predicting hearing aid use in a larger population. The results for 191 subjects are presented in this issue of JAAA and indicate that ANL is a useful predictor of success with hearing aids. The successful hearing aid users were defined as listeners who were able to use their hearing aids whenever they needed them. The unsuccessful hearing aid users were those who used their hearing aids only occasionally in easy listening conditions or stopped using their hearing aids altogether. The other papers in this special issue are extensions of the first, Nabelek et al. Freyaldenhoven, Smiley, et al posed an intriguing question regarding whether the ANL can be predicted from individual preference for background noise in everyday life. It is known that many people prefer some background sounds over total quiet during their work. Is that preference related to ANL? The study by von Hapsburg and Bahng demonstrated that the ANL can be assessed in languages other than English. Because some earlier ANL data were collected for monaural listening, Freyaldenhoven, Plyler, et al compared the ANLs for monaural and binaural hearing aid users and demonstrated that the results were not statistically different. There were, however, some individual differences that might be important for utilization of the ANL in clinical practice. Harkrider and Tampas demonstrated that for listeners with normal hearing, some brain responses were different for