Frequency compression hearing aid for severe-to-profound hearing impairments

(1) Objective: Objective of this study is to know how a frequency compression hearing aid with new concepts is beneficial for severe-to-profound hearing impairments. (2) Methods: Clinical trials of this hearing aid were conducted for 11 severe-to-profound hearing impaired listeners. These 11 wore the frequency compression hearing aid in their daily life and reported subjectively on its performance. Speech recognition tests with five listeners and audio-visual short sentence recognition tests with three listeners were also conducted. This hearing aid can separately adjust the fundamental frequency from the spectral envelope of input speech and can adjust frequency response by use of a post-processing digital filter. (3) Results: Five listeners out of these 11 came to prefer this hearing aid in their daily life and are still wearing it. The results of the speech recognition tests show that the speech recognition scores were not improved for all listeners and the results of the audio-visual short sentence recognition tests do that the audio-visual recognition scores were improved for two listeners. (4) Conclusion: There were some severe-to-profound hearing impaired listeners who preferred the frequency compression hearing aid finally. It is also suggested that the benefits of this hearing aid may be evaluated correctly using not only speech but also visual materials.     

Hearing aid fitting by prescription.

A procedure for the specification of hearing aid response characteristics is described. Thresholds of discomfort and most comfortable levels for narrow bands of noise centered at 0.25, 0.5, 1, 2, 3 and 4 kHz are determined. The thresholds of discomfort relate to the maximum power output of the hearing aid and the most comfortable levels determine the gain and frequency response that will be required. The data derived from these measurements are given to the hearing aid dispenser who provides a hearing aid that matches the prescribed response characteristics. This technique requires less time than the conventional hearing aid evaluation procedure, and it provides the audiologist with measures of auditory function that can be directly related to hearing aid parameters.     

Hearing Aid Fitting by Prescription

A procedure for the specification of hearing aid response characteristics is described. Thresholds of discomfort and most comfortable levels for narrow bands of noise centered at 0.25, 0.5, 1, 2, 3 and 4 kHz are determined. The thresholds of discomfort relate to the maximum power output of the hearing aid and the most comfortable levels determine the gain and frequency response that will be required. The data derived from these measurements are given to the hearing aid dispenser who provides a hearing aid that matches the prescribed response characteristics

This technique requires less time than the conventional hearing aid evaluation procedure, and it provides the audiologist with measures of auditory function that can be directly related to hearing aid parameters     

The real ear effect of adjusting the tone control and venting a hearing aid system

The effect of modifying the frequency response of a hearing aid system has previously been reported only on 2 cc couplers. Although it is recognized that coupler measurements do not accurately reflect real ear measures, they are frequently quoted when describing the effect of modifying a hearing aid system. To investigate the correlation, the real ear effect was assessed in 43 ears by measuring the effect on the insertion gain of adjusting the tone control of a hearing aid and acoustically venting the mould with a 2 mm parallel vent, singly and in combination. The results were considerably different from those measured in couplers. By comparing insertion gain with 2 cc coupler gain measurements, it was found that: (1) adjusting the tone control had a lesser mean effect than predicted; (2) venting the earmould with a 2 mm parallel vent produced a mean reduction in the frequency response at 0.75 to 1 kHz of 8 dB SPL; (3) by combining a 2 mm earmould vent and adjusting the tone control, a mean reduction in the frequency response of 10 dB SPL was produced at 0.75 to 1 kHz. In addition, the range of acoustical effects was considerable, from virtually none to greater than those predicted in coupler experiments. This was presumably due to variation in the anatomy of normal canals. It is concluded that for both research and clinical purposes, the effect of modifying the frequency response of a hearing aid system should be measured by insertion gain rather than predicted from laboratory results.     

Some effects of FM-system coupling on hearing aid characteristics

A variety of electroacoustic characteristics was measured on four hearing aids and then repeated with the hearing aids connected to two different FM systems via three coupling methods: direct input, neck loop, and silhouette inductor. The measurements included frequency response, harmonic distortion, noise levels, input-output functions, and FM receiver volume control wheel taper curves. Omnidirectional and directional FM microphones were compared in a classroom environment, and minor changes in hearing aid-silhouette coupling were investigated. Large differences were found in some frequency response comparisons, with no single coupling method providing consistently better agreement with the hearing aid alone response. With the exception of the silhouette inductor, distortion and noise levels were similar for the hearing aids and FM-hearing aid combinations. Differences in the input-output functions between the hearing aids and the FM systems were observed. Some FM-hearing aid combinations produced very nonlinear FM receiver volume control wheel taper curves. The output level of a broadband noise in a classroom was reduced when a directional FM microphone was compared to the omnidirectional version. The results indicate that it cannot be assumed that the electroacoustic characteristics of a personal hearing aid are preserved when it is connected to an FM system.     

Optimum side for fitting a monaural hearing aid. 1. Patients' preference

The criteria generally used to decide in which ear to fit a monaural hearing aid are based on theory or anecdote and have not been verified by experimental observation. In this study to determine optimum side of fitting, 58 new hearing aid users were fitted with a hearing aid in one ear for 10 weeks, and then fitted in the other ear for a further 10 weeks. Subsequently, the subjects were asked their preference for side of hearing aid use and their reasons for this preference. 30 (52%) subjects reported better hearing with their aid in one ear than in the other; 24 (80%) of these preferred the ear with the poorer half-peak level elevation on a speech audiogram. The remaining 28 (48%) reported no difference in their aided hearing ability between ears, though 20 preferred one ear for practical reasons, unrelated to audiometric parameters. A patient's preference for side of fitting can be predicted from audiometric data but with only modest reliability. It is, therefore, recommended that bilateral ear moulds should be routinely provided for bilateral mild to moderate hearing impairment (speech frequency average less than 75 dB HL). If it is decided that only one ear mould should be provided, this should be made for the poorer hearing ear. The poorer hearing ear is best identified from the half-peak level elevation on a speech audiogram.     

Personality, hearing problems, and amplification characteristics: contributions to self-report hearing aid outcomes

OBJECTIVE: When we evaluate the success of a hearing aid fitting, or the effectiveness of new amplification technology, self-report data occupy a position of critical importance. Unless patients report that our efforts are helpful, it is difficult to justify a conclusion that the intervention has been successful. Although it is generally assumed that subjective reports primarily reflect the excellence of the fitted hearing aid(s) within the context of the patient's everyday circumstances, there is relatively little research that assesses the validity of this assumption. In previous work, we have reported some contributions of the service delivery setting (private practice versus public health) to self-report outcomes. The purpose of the present investigation was to assess the relative contributions of patient variables (such as personality and hearing problems) and amplification variables (such as soft sound audibility, gain and maximum output) to self-reports of hearing aid fitting outcomes. DESIGN: A cross-sectional survey of 205 patients was conducted with cooperation of eleven Audiology clinics. All subjects were recruited when they were seeking new hearing aids. Before the hearing aid fitting, measurements of personality and response bias were made, as well as measures of hearing problems and expectations about amplification. At the fitting, traditional verification data were measured including sound field thresholds, preferred gain for conversation, and maximum output. Six months after the fitting, a set of 12 standardized self-report outcomes was completed. Analyses concerned: (1) the associations among personality, response bias, and self-reports about hearing problems that are available before the hearing aid fitting, and (2) the associations of these precursor variables, and fitting verification data, with self-report data assessing the outcome of hearing aid provision. RESULTS: Self-reports of hearing problems, sound aversiveness, and hearing aid expectations obtained before the fitting were found to be more closely related to the strength of certain personality traits than to audiometric hearing loss. Response bias also was associated with personality variables. Analyses of the collection of outcome measures produced a set of three components that were interpreted as a Device component, a Success component, and an Acceptance component. The Device component was construed as reflecting characteristics of the hearing aid whereas the two other components were construed as reflecting attributes of the wearer. The Success and Acceptance components were each significantly associated with several personality traits, but the Device component was not associated with personality. Variables available before the fitting accounted for 20 to 30% of each outcome component whereas amplification variables measured to verify the fitting accounted for only 10% on only one component. CONCLUSIONS: As reported in previous research, personality is associated with self-report outcome data. However, if practitioners utilize existing measures of hearing problems at the prefitting stage, separate personality data will not yield additional leverage in prediction of long-term fitting outcomes. Traditional fitting verification data as measured in this study, proved minimally useful in prediction of long-term outcomes of the fitting. A large proportion of variance in self-report fitting outcomes has yet to be accounted for. Finally, it appears that certain types of questionnaires might be more appropriate for research evaluating new amplification devices, whereas a different questionnaire approach might be optimal for evaluating intervention effectiveness in a clinical context.     

Hearing loss in over-65s: is routine questionnaire screening worthwhile?

It has been suggested that there is considerable unmet need in respect of hearing loss amongst the elderly population, but no routine screening test is currently used in general practice to identify these patients. The aim of this study was to determine whether routine questionnaire screening of the over-65s is a feasible way to identify elderly patients with hearing loss in primary care and whether patients so identified would benefit from hearing aid fitting. A cohort of patients consisting of a sample of 234 individuals aged between 65 and 74, attending a doctor's surgery over a specified period, received a scored questionnaire to complete based on the Hearing Handicap Inventory for the Elderly Screening test. Hearing aid owners and those with a hearing handicap were identified, and non-aid wearers with handicap offered examination and referral. Those patients who were fitted with aids were assessed after six months for aid usage and persisting handicap. Twenty-five per cent of the patient sample reported a previously undiagnosed hearing handicap. Six months after aid fitting, a reduction in hearing handicap was reported in 79 per cent of these cases and overall aid usage in the population sample had increased from nine per cent to 20 per cent. Routine questionnaire screening in general practice may be worthwhile since it is easy to carry out and the resulting intervention significantly reduces reported hearing handicap.     

Hearing aid patients in private practice and public health (Veterans Affairs) clinics: are they different?

OBJECTIVE: In hearing aid research, it is commonplace to combine data across subjects whose hearing aids were provided in different service delivery models. There is reason to question whether these types of patients are always similar enough to justify this practice. To explore this matter, this investigation evaluated similarities and differences in self-report data obtained from hearing aid patients derived from public health (Veterans Affairs, VA) and private practice (PP) settings. DESIGN: The study was a multisite, cross-sectional survey in which 230 hearing aid patients from VA and PP audiology clinic settings provided self-report data on a collection of questionnaires both before and after the hearing aid fitting. Subjects were all older adults with mild to moderately severe hearing loss. About half of them had previous experience wearing hearing aids. All subjects were fitted with wide-dynamic-range-compression instruments and received similar treatment protocols. RESULTS: Numerous statistically significant differences were observed between the VA and PP subject groups. Before the fitting, VA patients reported higher expectations from the hearing aids and more severe unaided problems compared with PP patients with similar audiograms. Three wks after the fitting, VA patients reported more satisfaction with their hearing aids. On some measures VA patients reported more benefit, but different measures of benefit did not give completely consistent results. Both groups reported using the hearing aids an average of approximately 8 hrs per day. VA patients reported age-normal physical and mental health, but PP patients tended to report better than typical health for their age group. CONCLUSIONS: These data indicate that hearing aid patients seen in the VA public health hearing services are systematically different in self-report domains from those seen in private practice services. It is therefore risky to casually combine data from these two types of subjects or to generalize research results from one group to the other. Further, compared with PP patients, VA patients consistently reported more favorable hearing aid fitting outcomes. Additional study is indicated to explore the determinants of this result and its generalizability to other public health service delivery systems such as those in other countries. Moreover, efforts should be made to assess the potential for transferring positive elements from the VA system to the PP service delivery system, if possible.     

Hearing aid benefit in patients with high-frequency hearing loss

Patients with hearing loss limited to frequencies above 2 kHz are often considered borderline candidates for hearing aids. In this study, we used the Profile of Hearing Aid Benefit to access 134 patients' perceived benefit with a variety of linear hearing aids, some more capable than others at achieving prescribed frequency gain targets. We also sought to explore various audiologic and subject factors that might have led patients to report different degrees of success or failure with their hearing aids. Results demonstrate that subjects with hearing loss limited to frequencies above 2 kHz benefit significantly from amplification. However, the amount of benefit reported is mostly unrelated to the hearing aid gain and frequency response. Of numerous audiologic and demographic factors explored in the present study, the number of hours of hearing aid use per day turned out to be the most important single factor that was significantly related to the amount of reported hearing aid benefit. However, the predictive value of knowing how many hours per day subjects wore their aids, or any other combination of factors explored, was quite limited and only accounted for a small amount of the variability observed in user benefit.     

Self-reported benefits of hearing aids by the hearing impaired

Benefits of hearing aids were studied in a group of 169 patients using an open-ended self-report approach. The overall pattern of benefits was qualitatively similar to the pattern of complaints reported by candidates for hearing aids (Golabek et al., 1988). The response pattern was related to the age and work of the hearing aid users, to the level of the hearing loss in the better ear and to the amount of use of the hearing aid.     

Hearing Aid Possession in the Population: Lessons from a Small Country: Posesión de auxiliares auditivos en la población: Lecciones de un pequeño pais

The results of several studies on hearing aid use in the Welsh population were considered to investigate some general principles on determinants of such use within the general populations of developed countries. Overall hearing aid possession and use were not found to have changed significantly over the past 18 years, remaining at 4 per cent having obtained hearing aids and 3 per cent using them. The possession figures were consistent across all methodologies used. Higher hearing aid use in the post-industrial valleys (in which the traditional industries of coal mining and steel production had disappeared) was explained entirely by a higher level of reported hearing difficulties there. In all populations, less than 20 per cent of those reporting difficulties possessed hearing aids. Whether a hearing aid had been obtained free of charge from the National Health Service or purchased privately did not influence whether it was still used. It was concluded that an effort to improve the acceptability of hearing aids and reduce their stigma is required.     

Hearing aid possession in the population: lessons from a small country.

The results of several studies on hearing aid use in the Welsh population were considered to investigate some general principles on determinants of such use within the general populations of developed countries. Overall hearing aid possession and use were not found to have changed significantly over the past 18 years, remaining at 4 per cent having obtained hearing aids and 3 per cent using them. The possession figures were consistent across all methodologies used. Higher hearing aid use in the post-industrial valleys (in which the traditional industries of coal mining and steel production had disappeared) was explained entirely by a higher level of reported hearing difficulties there. In all populations, less than 20 per cent of those reporting difficulties possessed hearing aids. Whether a hearing aid had been obtained free of charge from the National Health Service or purchased privately did not influence whether it was still used. It was concluded that an effort to improve the acceptability of hearing aids and reduce their stigma is required.     

Analysis of counted behaviors in a single-subject design: modeling of hearing-aid intervention in hearing-impaired patients with Alzheimer's disease

Clinical procedures related to patients with Alzheimer's Disease (AD) largely fail to address the patient's hearing. Given the challenges of this population, unconventional indicators of treatment efficacy may be required. Palmer et al (1999) reported on caregiver-tracked behaviors as outcome measures for hearing aid intervention. Using these data, hearing aid use and subsequent behavior was modeled as a first-order dynamic system, characterized by responses following an exponential time course. The results of such modeling suggest predictable outcomes of hearing aid intervention, or at least useful parameters of quantification (e.g. time-constant and steady-state response), permitting critical assessment of effects of intervention on negative behaviors versus hearing aid use, comparisons among behaviors, and/or comparisons of hearing-aid-use patterns and behavior counts among patients. Use in this and other difficult-to-test populations warrant further study to evaluate clinical efficacy of the analysis described.     

Experience with a subcutaneous implantable bone conduction hearing aid (Xomed Audiant) in a district general hospital.

Patients with a conductive hearing loss may find conventional hearing aids unsatisfactory for a variety of reasons. Efforts to overcome some of these difficulties have led to the development of the osteointegrated hearing aid. Implantable bone conduction hearing aids are an important advance in the treatment of well selected patients. Only 18 patients, who have been implanted with the Xomed Audiant bone conduction hearing aid, have so far been reported on in the UK. This report concerns a further six patients who have been implanted in one centre. Five of these patients continue to use their Audiant hearing aid 14 to 24 months after being fitted. They regard it to have significant advantages over their previous hearing aids. Four of the five patients use an ear level processor. Two of the patients who had previously used conventional bone conduction hearing aids now use the ear level processor.     

Analysis of counted behaviors in a single-subject design: modeling of hearing-aid intervention in hearing-impaired patients with Alzheimer's disease Análisis del conteo de conductas en un diseño unipersonal: Modelo de intervención con auxiliar auditivo en pacientes hipoacúsicos con enfermedad de Alzheimer

Clinical procedures related to patients with Alzheimer's Disease (AD) largely fail to address the patient's hearing. Given the challenges of this population, unconventional indicators of treatment efficacy may be required. Palmer et al (1999) reported on caregiver-tracked behaviors as outcome measures for hearing aid intervention. Using these data, hearing aid use and subsequent behavior was modeled as a first-order dynamic system, characterized by responses following an exponential time course. The results of such modeling suggest predictable outcomes of hearing aid intervention, or at least useful parameters of quantification (e.g. time-constant and steady-state response), permitting critical assessment of effects of intervention on negative behaviors versus hearing aid use, comparisons among behaviors, and/or comparisons of hearing-aid-use patterns and behavior counts among patients. Use in this and other difficult-to-test populations warrant further study to evaluate clinical efficacy of the analysis described.     

Identifying the barriers and facilitators to optimal hearing aid self-efficacy

Abstract

Objective: Many older adults with hearing impairment are not confident in their ability to use hearing aids (i.e. experience low hearing aid self-efficacy), which has been found to be a barrier to hearing help-seeking and hearing aid use. This study aimed to determine what factors were associated with achieving adequate hearing aid self-efficacy. Design: A retrospective research design was employed wherein hearing aid self-efficacy was the primary outcome. Explanatory variables included personal demographics, visual disability, and experiences related to participants’ hearing ability and hearing aids. Study sample: A total of 307 older adults with hearing impairment participated in the study (147 non hearing aid owners and 160 hearing aid owners). Results: Non-hearing aid owners were more likely to report adequate hearing aid self-efficacy if they reported no visual disability, had experienced hearing loss for longer, reported more positive support from a significant other, and were not anxious about wearing hearing aids. Hearing aid owners were more likely to report adequate hearing aid self-efficacy if they had had a positive hearing aid experience and no visual disability. Conclusions: More research is needed to develop and evaluate intervention approaches that promote optimal levels of hearing aid self-efficacy among older adults with hearing impairment.     

Cognitive function in relation to hearing aid use

Two experiments were conducted to investigate possible relationships between cognitive function and hearing aid use. In Experiment 1, 72 first-time hearing aid users were tested for speech recognition in noise (Hagerman sentence test) with and without hearing aids. Cognitive function was assessed by tests of working memory (reading span test) and verbal information-processing speed. The results indicate that, after controlling for age and hearing loss, significant correlations exist between the measures of cognitive performance and speech recognition in noise, both with and without hearing aids. High cognitive performance was associated with high performance in the speech recognition task. In Experiment 2, 17 first-time hearing aid users with either high or low working-memory capacity tested an experimental hearing aid which processed the sound differently depending on whether or not speech was detected. The results revealed that those with high working-memory capacity were better than those with low capacity at identifying and reporting the specific processing effects of the aid. This may have implications for how reported results should be interpreted in a research context, how a person's rehabilitation needs are formulated, and how hearing aid controls should be supervised. In conclusion, careful attention should be paid to the cognitive status of listeners, as it can have a significant influence on their ability to utilize their hearing aids.     

The bone-anchored hearing aid. Principal design and a psychoacoustical evaluation

Hearing aids can be divided into two groups, distinguished by the principle of how sound is transmitted to the cochlea. The greatest and most important group is that consisting of air conduction (AC) hearing aids, whereas the other group consisting of bone conduction (BC) hearing aids is relatively small but nevertheless important for patients with particular types of hearing disorder. Conventional bone conduction hearing aids are not in common use, mainly because of several drawbacks. The implantation of a titanium screw into the mastoid portion of the temporal bone has made it possible to obtain a permanent and reaction-free rigid penetration of the skin. A newly developed bone conduction hearing aid was connected to such a screw. This new hearing aid is named 'the bone-anchored hearing aid' (BAHA) and it is characterized by a single housing construction. The transducer piston of the BAHA is directly connected to the titanium screw by a low-profile coupling arrangement. Ten patients were equipped with this new hearing system. In a comprehensive questionnaire, all patients reported that they preferred the BAHA to their old hearing aid. The major reasons were improvements in practical arrangements, wearing comfort, aesthetic appearance, and sound quality. Improvements in speech reception were not verified by the discrimination tests, but 6 out of 10 patients subjectively reported clearly improved sound quality. The group of patients who may benefit from the BAHA of present standard includes patients with a sensorineural hearing loss of at most 50-60 dB HL.