Amplification and Aural Rehabilitation Maturation of Hearing Aid Benefit : Objective and Subjective Measurements

The goals of this investigation were to determine whether hearing aid benefit improved significantly over the first 10 weeks of hearing aid use and whether time-related changes in benefit (if any) were affected by the type of benefit measurement (i.e., objective or subjective). A total of 17 hearing-impaired subjects participated, with different subjects completing different phases of the study. Benefit was measured soon after the hearing aid fitting and again after 10 weeks of adjustment to hearing aid use. Objective benefit data were determined using the Connected Speech Test. No significant changes in objective benefit were noted in noisy or reverberant listening environments when visual cues were available. However, in a low-noise setting and in a noisy setting without visual cues, improvements in objective benefit were seen over time. Subjective benefit data were derived from responses to the Profile of Hearing Aid Benefit. These data indicated significant benefit improvement over time in all five types of daily life situations assessed, although the improvement was small in reverberant and noisy environments. Significant, but modest, correlations were found between objective and subjective data for low-noise and reverberant listening environments. Comparison of experienced and novice hearing aid wearers suggested that although experienced wearers obtain more benefit than novice wearers, they evidence similar time-related changes in benefit during the first 10 weeks of new hearing aid use. (Ear Hear 13 3:131-141) FOR MOST HEARING AID wearers, improved ability to understand speech in daily life is the major component of hearing aid benefit. As a result, speech understanding is often measured during hearing aid fitting and the results may be a major factor in determining amplification recommendations. For example, the difference between clinically measured aided and unaided speech understanding is often used to predict the hearing aid benefit that can be expected from the fitting. Nevertheless, there is a surprising paucity of data that establish the validity of this practice. In other words, we cannot assert with confidence that hearing aid benefit (aided versus unaided speech understanding) measured at the time the instrument is fitted can be used with accuracy to predict the daily life benefit that will ultimately be obtained from the fitting. Validated procedures are urgently needed for predicting long-term benefit on the day the hearing aid is fitted. The most popular approach to quantification of longterm benefit of a hearing aid fitting uses a self-report questionnaire in which the experienced hearing aid wearer subjectively assesses the benefit provided by the instrument in daily life. Long-term subjective assessments of benefit have sometimes been compared with objective benefit measurements (i.e., speech understanding scores) that were acquired during the initial hearing aid fitting. This comparison reveals whether the early objective measures could be used to predict the long-term subjective data. Most of these studies have reported a negative outcome. That is, objective measures of speech understanding obtained during the hearing aid fitting were not found to be closely related to the long-term subjective benefit of the instrument (e.g., Haggard, Foster, & Iredale, 1981; Scherr, Schwartz, & Montgomery, 1983; Stroud & Hamill, 1989; SUIT, Schuchman, & Montgomery, 1978) A factor that complicates the prediction of long-term hearing aid benefit is the learning or adjustment process that follows the acquisition of a hearing aid. It is well established that most hearing aid wearers require at least several weeks of hearing aid use before they report that they are “adjusted” to the instrument (e.g., Berger & Hagberg, 1982; Kapteyn, 1977). This adjustment must be partly physical in that the user is learning to manipulate the instrument. However, it also may encompass a learning process during which speech understanding with the hearing aid is optimized. Barfod (1979) has utilized a speech perception model to propose an explanation for this optimization process. The model postulates a preliminary auditory analysis followed by a “recognition device. ” The preliminary auditory analysis converts the incoming acoustic signal into neural impulses. The recognition device matches these neural patterns with previously learned data to determine the spoken phonemes. Amplification, especially when it is frequency dependent, modifies the 01 96/0202/92/1303-0131$03.00/0 . EAR AND HEARING Copyright