Impact of Hearing Aid Technology on Outcomes in Daily Life III: Localization.

OBJECTIVE: Compared to basic-feature hearing aids, premium-feature hearing aids have more advanced technologies and sophisticated features. The objective of this study was to explore the difference between premium-feature and basic-feature hearing aids in horizontal sound localization in both laboratory and daily life environments. We hypothesized that premium-feature hearing aids would yield better localization performance than basic-feature hearing aids. DESIGN: Exemplars of premium-feature and basic-feature hearing aids from two major manufacturers were evaluated. Forty-five older adults (mean age 70.3 years) with essentially symmetrical mild to moderate sensorineural hearing loss were bilaterally fitted with each of the four pairs of hearing aids. Each pair of hearing aids was worn during a 4-week field trial and then evaluated using laboratory localization tests and a standardized questionnaire. Laboratory localization tests were conducted in a sound-treated room with a 360°, 24-loudspeaker array. Test stimuli were high frequency and low frequency filtered short sentences. The localization test in quiet was designed to assess the accuracy of front/back localization, while the localization test in noise was designed to assess the accuracy of locating sound sources throughout a 360° azimuth in the horizontal plane. RESULTS: Laboratory data showed that unaided localization was not significantly different from aided localization when all hearing aids were combined. Questionnaire data showed that aided localization was significantly better than unaided localization in everyday situations. Regarding the difference between premium-feature and basic-feature hearing aids, laboratory data showed that, overall, the premium-feature hearing aids yielded more accurate localization than the basic-feature hearing aids when high-frequency stimuli were used, and the listening environment was quiet. Otherwise, the premium-feature and basic-feature hearing aids yielded essentially the same performance in other laboratory tests and in daily life. The findings were consistent for both manufacturers. CONCLUSIONS: Laboratory tests for two of six major manufacturers showed that premium-feature hearing aids yielded better localization performance than basic-feature hearing aids in one out of four laboratory conditions. There was no difference between the two feature levels in self-reported everyday localization. Effectiveness research with different hearing aid technologies is necessary, and more research with other manufacturers' products is needed. Furthermore, these results confirm previous observations that research findings in laboratory conditions might not translate to everyday life.

Impact of Hearing Aid Technology on Outcomes in Daily Life II: Speech Understanding and Listening Effort.

OBJECTIVES: Modern hearing aid (HA) devices include a collection of acoustic signal-processing features designed to improve listening outcomes in a variety of daily auditory environments. Manufacturers market these features at successive levels of technological sophistication. The features included in costlier premium hearing devices are designed to result in further improvements to daily listening outcomes compared with the features included in basic hearing devices. However, independent research has not substantiated such improvements. This research was designed to explore differences in speech-understanding and listening-effort outcomes for older adults using premium-feature and basic-feature HAs in their daily lives. DESIGN: For this participant-blinded, repeated, crossover trial 45 older adults (mean age 70.3 years) with mild-to-moderate sensorineural hearing loss wore each of four pairs of bilaterally fitted HAs for 1 month. HAs were premium- and basic-feature devices from two major brands. After each 1-month trial, participants' speech-understanding and listening-effort outcomes were evaluated in the laboratory and in daily life. RESULTS: Three types of speech-understanding and listening-effort data were collected: measures of laboratory performance, responses to standardized self-report questionnaires, and participant diary entries about daily communication. The only statistically significant superiority for the premium-feature HAs occurred for listening effort in the loud laboratory condition and was demonstrated for only one of the tested brands. CONCLUSIONS: The predominant complaint of older adults with mild-to-moderate hearing impairment is difficulty understanding speech in various settings. The combined results of all the outcome measures used in this research suggest that, when fitted using scientifically based practices, both premium- and basic-feature HAs are capable of providing considerable, but essentially equivalent, improvements to speech understanding and listening effort in daily life for this population. For HA providers to make evidence-based recommendations to their clientele with hearing impairment it is essential that further independent research investigates the relative benefit/deficit of different levels of hearing technology across brands and manufacturers in these and other real-world listening domains.

Impact of Hearing Aid Technology on Outcomes in Daily Life I: The Patients' Perspective.

OBJECTIVES: One of the challenges facing hearing care providers when recommending hearing aids is the choice of device technology level. Major manufacturers market families of hearing aids that are described as spanning the range from basic technology to premium technology. Premium technology hearing aids include acoustical processing capabilities (features) that are not found in basic technology instruments. These premium features are intended to yield improved hearing in daily life compared with basic-feature devices. However, independent research that establishes the incremental effectiveness of premium-feature devices compared with basic-feature devices is lacking. This research was designed to explore reported differences in hearing abilities for adults using premium- and basic-feature hearing aids in their daily lives. DESIGN: This was a single-blinded, repeated, crossover trial in which the participants were blinded. All procedures were carefully controlled to limit researcher bias. Forty-five participants used carefully fitted bilateral hearing aids for 1 month and then provided data to describe the hearing improvements or deficiencies noted in daily life. Typical participants were 70 years old with mild to moderate adult-onset hearing loss bilaterally. Each participant used four pairs of hearing aids: premium- and basic-feature devices from brands marketed by each of two major manufacturers. Participants were blinded about the devices they used and about the research questions. RESULTS: All of the outcomes were designed to capture the participant's point of view about the benefits of the hearing aids. Three types of data were collected: change in hearing-related quality of life, extent of agreement with six positively worded statements about everyday hearing with the hearing aids, and reported preferences between the premium- and basic-feature devices from each brand as well as across all four research hearing aids combined. None of these measures yielded a statistically significant difference in outcomes between premium- and basic-feature devices. Participants did not report better outcomes with premium processing with any measure. CONCLUSIONS: It could reasonably be asserted that the patient's perspective is the gold standard for hearing aid effectiveness. While the acoustical processing provided by premium features can potentially improve scores on tests conducted in contrived conditions in a laboratory, or on specific items in a questionnaire, this does not ensure that the processing will be of noteworthy benefit when the hearing aid is used in the real world challenges faced by the patient. If evidence suggests the patient cannot detect that premium features yield improvements over basic features in daily life, what is the responsibility of the provider in recommending hearing aid technology level? In the present research, there was no evidence to suggest that premium-feature devices yielded better outcomes than basic-feature devices from the patient's point of view. All of the research hearing aids were substantially, but equally, helpful. Further research is needed on this topic with other hearing aids and other manufacturers. In the meantime, providers should insist on scientifically credible independent evidence to support effectiveness claims for any hearing help devices.

Impact of advanced hearing aid technology on speech understanding for older listeners with mild to moderate, adult-onset, sensorineural hearing loss.

BACKGROUND: Hearing loss is one of the most common chronic health conditions of older people. Hearing aids are the customary treatment and they improve quality of life in older adults. Even so, relatively few older adults with uncomplicated, mild to moderate, adult-onset, sensorineural hearing loss use hearing aids. One reason for this is a belief that hearing aids do not provide sufficient value to justify their expense. Although modern hearing aids are available at several price points, there is minimal evidence about the relative benefits of premium-level versus basic-level hearing aid technologies. OBJECTIVE: This research was designed to demonstrate the relative effectiveness of premium hearing aids compared with basic hearing aids in improving speech understanding and quality of life. METHODS: 25 participants, including both new and experienced hearing aid users, completed blinded month-long field trials with each of four pairs of hearing aids: two basic and two premium level. Outcomes were laboratory speech understanding tests, standardized questionnaires and open-ended diary items. RESULTS: Participants reacted very positively to all the hearing aids. Both everyday speech understanding and quality of life were substantially improved with hearing aids. RESULTS for both new and experienced users were consistent with a conclusion that there were no statistically significant or clinically important differences in improvement between the premium- and basic-level hearing aids. CONCLUSIONS: It should not be assumed that more costly hearing aids always produce better outcomes. With contemporary hearing aids from two major manufacturers, the subjects obtained as much improvement in speech understanding and quality of life from lower-cost basic-level instruments as from higher-cost premium-level instruments. Regardless of technology level, comprehensive best-practice fitting protocols should be followed to optimize results for every patient.

Implications of high-frequency cochlear dead regions for fitting hearing aids to adults with mild to moderately severe hearing loss.

OBJECTIVES: A cochlear dead region (DR) occurs at a given frequency when there is a loss of normal functioning of inner hair cells tuned to that frequency. It has been suggested that existence of high-frequency DRs has implications for hearing aid fitting, and that the optimal amount of high-frequency gain is reduced for these patients. However, the data supporting this suggestion has been obtained using listeners with severe or profound hearing loss. It is uncertain whether these results would apply for listeners with the mild to moderately severe hearing loss that is more typical of hearing aid users. This investigation used laboratory and field measurements to examine the effects of reduced high-frequency gain in typical hearing aid users with high-frequency DRs compared with matched users without DRs. DESIGN: The study was a double-blinded, nonrandomized intervention design with 18 matched pairs of adult subjects. In each pair, one subject had high-frequency DRs (usually at one or two test frequencies) and the other subject had no DR. Each subject was fitted unilaterally with a hearing aid having two active programs. One program used a National Acoustics Laboratories (NAL) prescription target for average speech (NAL condition). The other program was identical to NAL except for reduced gain in the high frequencies (low-pass [LP] condition). Outcomes included aided speech recognition in quiet and noise measured in the laboratory, ratings of speech understanding in daily life, and final preference for the NAL or LP program. RESULTS: In laboratory testing, speech recognition in quiet was significantly better when using the NAL program. This result was seen for subjects with DRs and without DRs. When listening in noise, speech recognition was significantly better when using the NAL program for subjects without DRs. For subjects with DRs, results were equivalent for the NAL and LP programs. In daily life, the NAL program received significantly higher ratings for speech understanding, and this result was seen for subjects with and without DRs. When asked about their preference for using the NAL or LP program in daily life, subjects did not always choose the program they had rated as giving better speech understanding, but their preference was not associated with having DRs. About one-third of subjects preferred the LP program. The reason most frequently given for preferring the LP program was that the NAL was too loud. CONCLUSIONS: Overall, adult hearing aid wearers with mild to moderately severe hearing loss benefitted from high-frequency gain whether or not they had DRs. In laboratory testing, but not in daily life, subjects with DRs tended to obtain less benefit than those without DRs. However, provision of NAL high-frequency gain never resulted in poorer performance in either group. These results suggest that identification of high-frequency DRs at one or two frequencies does not call for any a priori modification of the target hearing aid prescription for listeners with mild to moderately severe hearing loss.

Development of APHAB norms for WDRC hearing aids and comparisons with original norms.

OBJECTIVES: This study was undertaken for two purposes: First, to provide a comparison of subjective performance and benefit measured with the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire for two groups. One group included hearing-impaired individuals using 1990s-era linear processing hearing aids. The other group included hearing-impaired individuals using more current wide-dynamic range compression (WDRC)-capable hearing aids fit using current practice protocols. The second purpose of this study was to determine whether APHAB norms derived from scores for current hearing aid users were different from the original 1995 norms. It was hypothesized that technology improvements would result in improved subjective performance for modern hearing aid wearers. DESIGN: A systematic sampling method was used to identify and recruit subjects from seven private-practice audiology clinics located across the United States. Potential subjects were limited to older hearing-impaired individuals who were wearing hearing aids capable of WDRC processing. One hundred fifty-four subjects returned completed APHAB questionnaires. Participants reported mostly moderate to moderately severe subjective hearing difficulty. RESULTS: No differences in perceived difficulty with speech communication were observed between the two groups. However, aversiveness of amplified sound was less frequently reported for users of WDRC-capable hearing aids. Norms were generated using data from all of the operationally defined successful hearing aid users in the sample and compared with the original 1995 norms. Differences between the 1995 and 2005 norms were minimal for the speech communication subscales. However, the 2005 group consistently reported less frequent difficulties with sound aversiveness (AV subscale) in the aided condition. In addition to these findings, an improvement was observed in the rate of successful adjustment to hearing aids between 1995 (43%) and 2005 (82%). CONCLUSIONS: Overall, problems understanding amplified speech did not decrease in frequency when hearing aids transitioned from linear to compression processing; however, the compression capabilities of current hearing aids (with a possible contribution from noise reduction algorithms) have resulted in less negative reactions to amplified environmental sounds. This suggests that modern technology has ameliorated (to some extent) the common complaint that hearing aids cause many everyday sounds to become objectionably loud. Although the results of this study suggest that the advantages of improved technology do not lie in the domains of improved subjective speech communication performance, substantial improvement in the rate of successful adjustment to hearing aids between the 1995 and 2005 subject groups provides evidence that modern hearing aid technology has produced progress in other outcome domains.