Predicting Success With Hearing Aids

As numerous studies have reported, the most common complaint that individuals with sensorineural hearing loss have about their hearing is that they can hear speech but they cannot understand speech, especially in background noise. For this type of hearing loss and most other types of hearing losses, hearing aids are the intervention of choice. The majority of individuals who receive hearing aids are successful hearing-aid users in that both subjectively and objectively they function better with their hearing aids than without hearing aids. Other individuals are unsuccessful hearing-aid users because for a variety of reasons their perception is that the hearing aids do not enable them to function better. Two studies (Popelka et al., 1998; Kockchin, 2000) indicate that about 25% of individuals who receive hearing aids can be considered unsuccessful hearing-aid users. If potentially (un)successful hearing-aid users can be identified, then audiologic rehabilitation programs can be designed for use with potentially successful hearing-aid users and more extensive audiologic rehabilitation programs can be designed for use with those individuals who are potentially unsuccessful hearing-aid users.

Data from a recent series of studies by N b lek and her colleagues (1991, 2004) indicate that successful and unsuccessful hearing-aids users can be predicted based on their performance on a subjective speech-in-noise task in which a most comfortable listening level is established for a travelogue story and the level of a multitalker babble is established that permits following the travelogue. The difference between these two levels is the acceptable noise level (ANL). Based on the ANL data, N b lek et al. (2006) report with 85% confidence those individuals who are successful hearing-aid users and those who are unsuccessful hearing-aid users. One premise of this proposal is that the ANL is in fact an estimate in the subjective realm of the signal-to-noise (S/N) at which the listener is comfortable listening to a speech signal in background noise.

Recently in our laboratory the words-in-noise (WIN) test was developed that involves the presentation of words in multitalker babble at signal-to-babble (S/B) ratios from 24- to 0-dB in 4-dB decrements. The 50% point on the function is calculated with the Spearman-K rber equation. This objective instrument provides an average 8-dB separation in recognition performances between listeners with normal hearing and listeners with hearing loss. The 50% points for the listeners with normal hearing are 0- and 6-dB S/B, whereas the 50% points for the listeners with hearing loss are 8- and 16-dB S/B. Thus, not only is the WIN very sensitive to the effects of hearing loss on speech understanding, but the WIN provides a range of performances by listeners with hearing loss.

The proposed study is designed to answer the following two key questions:

1. What is the relationship between ANL performance (subjective paradigm) and WIN performance (objective paradigm) in both unaided and aided conditions?
2. How well do the ANL and WIN scores predict subjective hearing-aid outcome domains (use, satisfaction, benefit, and global)?

In addition, the study design enables multiple comparisons to be made among several of the study variables and among many traditional variables such as age, pure-tone thresholds, and word-recognition abilities in quiet.

Future goals beyond this proposal involve the development (1) of systematic protocols to select amplification devices or specific features for amplification based on WIN or ANL performance, and (2) of audiologic rehabilitation programs that can be administered quickly and effectively (depending on the category of hearing-aid success that was determined from performances on the WIN or ANL) to veterans who are receiving hearing aids.