Hearing Aid Evaluation Research Articles

A Tutorial on Complex Sound Fields for Audiometric Testing

A fundamental understanding of soundfield characteristics in enclosed spaces is required in order to appreciate and predict the behavior of complex sound fields (i.e., sound fields created with at least two uncorrelated sound sources on different axes) used in auditory tests for evaluating hearing aid performance, especially speech-in-noise tasks. This article is a tutorial starting with idealized definitions of acoustical spaces. Next is an exploration of the interactions between practical sound fields and the enclosures that contain them, based on a synthesis of ideas formed from a review of classical acoustical theory combined with direct observation. Finally, the discussion turns to the application of complex sound fields for speech-in-noise testing in typical audiometric test rooms and a practical realization of such a sound field with consideration given to the limitations imposed by factors covered in the foregoing discussions.

Selecting, verifying, and evaluating hearing aids for children

This article examines issues relating to selecting, verifying, and evaluating hearing aids that are vital to the provision of effective amplification for children. The physical effects of ear canal sizes on hearing assessment and hearing aid adjustment and verification are well understood, and solutions that are readily applicable are summarized. The issue of whether children need different real-ear frequency response and gain than adults with similar hearing losses is rather controversial. A background for understanding how and why two widely-used prescriptions for children differ is provided, followed by a review of research to address the commonly asked but unresolved questions of whether children need more high-frequency audibility and more overall gain than adults with similar hearing losses. Finally, a range of methods for evaluating individual fittings of children are described. These include functional assessment approaches, preference-based evaluations, and electrophysiologically-based measurements.

Societal effects of hearing aid fitting among the moderately hearing impaired: Efectos sociales de la adaptación de auxiliares auditivos en pacientes con impedimentos auditivos moderados

The objective of this study was to evaluate hearing aid fitting from a societal viewpoint, rather than the more traditional patient perspective. The effects of hearing aid fitting on generic quality of life (EuroQol), social functioning (SF36), auditory disability, productivity at paid and unpaid labour, and medical consumption, were assessed in a prospective study among 80 moderately hearingimpaired first-time hearing aid applicants. The study showed that hearing aid fitting solved problems with paid employment, but did not seem to affect unpaid work. Use of medical services remained relatively stable after first-time hearing aid fitting. The Amsterdam Inventory proved to be a useful questionnaire to assess the effects on hearing disability. No effects of hearing aid fitting on generic quality of life could be determined with the EuroQol, while hearing aid fitting did lead to an improvement in one aspect of generic quality of life; namely social functioning.El objetivo de este estudio fue evaluar la adaptación de auxiliares auditivos desde un punto de vista social, más que desde la perspective tradicional del paciente. Los efectos de la adaptación de auxiliares auditivos en la calidad genérica de vida (EuroQWol), funcionamiento social (SF36), discapacidad auditiva, productividad en el trabajo remunerado o no remunerado, además de gastos médicos, fueron evaluados en un estudio prospectivo con 80 pacientes con impedimentos auditivos moderados a quienes se les adaptó por primera vez un auxiliar auditivo. El estudio mostró que la adaptación de auxiliares auditivos resuelve problemas en los empleos remunerados pero no parece afectar el trabajo sin remuneración. El uso de servicios médicos permaneció relativamente estable después de la primera adaptación. El cuestionario Amsterdam probó ser un instrumento útil para evaluar los efectos en la discapacidad auditiva. No se pudieron determinar los efectos de la adaptación de auxiliares auditivos en la calidad genérica de vida por medio del EuroQol, mientras que la adaptación de auxiliares auditivos condicionó la mejoría en un aspecto de la calidad genérica de vida, que es concretamente, el funcionamiento social.

The National Acoustic Laboratories’ (NAL) CDs of Speech and Noise for Hearing Aid Evaluation: Normative Data and Potential Applications

This paper describes the speech and noise material on a new set of three CDs that is considered very suitable for hearing assessment and fine-tuning of hearing aids in audiological clinics. The material includes continuous discourses, various background noises, and three different speech test materials (BKB sentence test, four SPIN sentence lists, and Vowel-Consonant-Vowel (VCVs) nonsense syllables). All speech samples are recorded using native speakers of Australian English. Normative data in the form of the central part of performance-intensity functions are presented for the BKB sentences in babble-noise and for intelligibility rating of continuous discourse in nine background noises together with list-equivalence data for the BKB test. For each test, the critical difference that needs to be exceeded to obtain significantly different results is also presented. Applications for the material with respect to candidacy and hearing aid fine-tuning are discussed.

Loudness scaling in children

Loudness measurements in children have been carried out using different psychoacoustical methods. Besides absolute magnitude estimation (AME) and cross modality matching (CMM) category and non-category loudness scalings have been performed. However, there is a lack of systematic evaluation in loudness scalings with children. A clinically feasible categorical method is presented which was evaluated in 10 normally hearing children of 7 to 8 years. Furthermore, measurements with hearing disabled children were performed in the framework of hearing aid evaluation. Normal hearing children scaled slightly louder than a group of adult subjects with normal hearing. Regarding the shape of the loudness functions measured they were very similar. Particularly, they showed a steeper course at higher levels than for low input signals. Intraindividual scatter of the loudness judgements was larger for children than for adults. However, high correlation appeared between the data across test and retest. Hence, the outcome of the scalings appears to be sufficient reliable. Clinical measurements confirmed that the method is appropriate for children from approximately 5-10 years. Loudness judgements became more consistent and more subtly differentiated with increasing age and decreasing hearing loss. Especially with view of hearing aid evaluation the method can give valuable indications because of the possibility to directly measure individual loudness over a broad range of levels and frequencies.

Technology, Expectations, and Adjustment to Hearing Loss: Predictors of Hearing Aid Outcome

This study examined the influence of technology, demographic factors, and prefitting expectations, attitudes, and adjustment to hearing loss on hearing aid outcome. Clients obtaining new hearing aids completed questionnaires measuring personal adjustment to hearing loss, expectations of and attitudes toward hearing aids, and hearing aid benefit. Eighty-one percent of the 200 subjects completing the prefitting questionnaires returned questionnaires evaluating hearing aid outcome. Factors affecting hearing aid use, overall satisfaction, and benefit were investigated using regression analyses. Higher use time was associated with higher prefitting expectations and greater acceptance of hearing loss. Greater benefit in easy and difficult listening situations was predicted by higher prefitting expectations. Multiple-memory hearing aids produced higher satisfaction. Benefit was greater for multiple-memory, multiple-channel, and wide dynamic range compression aids. Findings were consistent with previous studies showing positive outcomes for newer technologies but also showed that two subjective factors, prefitting hearing aid expectations and acceptance of hearing loss, significantly influenced hearing aid outcome.

A holistic model for matching high-tech hearing aid features to elderly patients.

Successful hearing aid fittings using high-technology features for elderly patients require consideration of factors beyond results obtained from routine audiologic evaluations. A holistic hearing aid selection, fitting, and evaluation approach that considers patient characteristics from communication, physical, psychological, and social assessment domains is presented here along with a checklist and flowcharts for matching high-tech hearing aid features to older persons who are hearing aid candidates.

Digital hearing impairment simulation method and hearing aid evaluation method using the same

A digital hearing impairment simulation method and a hearing aid evaluation method using the same are disclosed. According to the digital hearing impairment simulation method, a hearing characteristic table of a hearing impaired person is input and the input table is stored in a memory, in order to sample the hearing characteristics of the hearing impaired person (S1). A hearing loss table is calculated and stored in the memory (S2). An audio signal input via an audio input portion is converted to a digital signal and the converted digital signal is stored in the memory (S3). The converted digital signal is converted to the frequency domain signal using a fast Fourier transform algorithm (S4). The average power by critical band is calculated (S5). A hearing loss gain for each critical band is calculated using the hearing loss table and the average powers of the critical bands (S6). Coefficients for a digital filter corresponding to the hearing loss gains of the critical bands is calculated (S7). The input signal converted to a digital signal and stored in the memory in the step (S3) is digitally filtered using the digital filter coefficients (S8). The digitally filtered signal is converted to an analog signal and the converted analog signal is output to an audio output portion (S9). Thus, the performance of a hearing aid can be easily evaluated and hearing characteristics of a hearing impaired person can be easily sampled.

Variable-speech-rate audiometry for hearing aid evaluation

A new hearing aid evaluation method using variable-speech-rate audiometry (VSRA) was developed. VSRA was newly created based on the Japanese speech audiometry authorized by the Japan Audiological Society. The ordinary speech audiometry can not reveal a temporal factor in word discrimination ability of the hearing impaired. Since, with VSRA, we can compare several performance-intensity curves obtained from different speech-rate speech audiometries, the impact on the auditory system of each patient by the fast or slow speech rate could be easily determined. Taking the temporal factor of the auditory systems into consideration by using VSRA, hearing aid evaluation was performed for a master hearing aid with three types of signal processing and fitting for 36 hearing impaired subjects. Then hearing aid evaluation was performed using VSRA for a newly developed portable multi-function digital hearing aid with two types of signal processing and analog hearing aids which had been used by hearing-impaired patients. As a result, VSRA was useful for hearing aid evaluation, in particular, for cases when ordinary normal speech rate audiometry does not provide a significant difference in word discrimination scores. In addition, using VSRA revealed that amplitude compression is more effective for improvement of word discrimination than linear amplification.

Relating hearing aid use to well-being among older adults

Julie A. Bridges, MA is a private practice audiologist at Hearing Aid Evaluations and Rehabilitation, Keokuk, IA. Ruth A. Bentler, PhD is Associate Professor, Department of Speech Pathology and Audiology, University of lowa. Correspondence to Dr. Bentler at her deportment, 121B S.H.C., University of lowa, lowa City, IA 52242.

Curriculum for graduate courses in amplification.

Curriculum for graduate courses in amplification.

Toward a Model Clinical-Trials Protocol for Substantiating Hearing Aid User-Benefit Claims

It has been argued that there is a need to adopt a uniform core set of dependent measures and test conditions for use in manufacturer-sponsored clinical trials to substantiate hearing device user-benefit claims in FDA applications. A framework for developing a model protocol was presented, and a core set of dependent measures and test conditions was suggested that may serve as a springboard for discussion. Given the state of the art, designing a protocol to evaluate hearing aid benefit requires that certain assumptions and compromises be made in defining this benefit and selecting test materials. The limitations of our knowledge and testing methods make it inevitable that the results of our efforts will not be perfect. The problems created by limited knowledge and methodology certainly are not unique to our discipline or to this endeavor. Although perfect prediction of everyday performance should be our goal, currently it cannot be our expectation. However, this should not deter us from our best attempt to reach our goal. The clinical-trials protocol described in this paper has been used in two manufacturer-sponsored clinical trials conducted at Walter Reed Army Medical Center. Although there has been general satisfaction with this protocol on the part of both the manufacturer and the researchers who have conducted these trials, the potential to improve this protocol certainly exists. The laboratory measures included in the Walter Reed protocol depend on traditional "objective" measures of speech recognition. There are other potentially useful methodologies (e.g., subjective ratings of intelligibility, paired-comparison techniques), and other dimensions of user performance (e.g., sound quality, loudness growth) that are ignored. Although the involvement of hearing researchers in manufacturer-sponsored clinical trials to substantiate user-benefit claims is relatively new, valuable experience has been gained in several clinical research laboratories. A collective effort on the part of manufacturers, researchers involved in this research activity, and government regulators, could lead to a model protocol that would benefit both hearing-impaired consumers and hearing instrument manufacturers.

Quality control in pediatric hearing aid fitting

Specific hearing aid selection and careful fitting are essential for successful rehabilitation of hearing-impaired children. For this reason the different hearing aid types prescribed, the type and frequency of hearing aid insufficiencies reported and the effectiveness and regularity of our follow-ups were studied evaluating 253 followup exams in 39 children (71 ears) suffering of a sensorineural hearing loss, including all degrees, supplied with a behind-the-ear hearing aid. Most of the devices had been prescribed outside our department on an initial trial basis. After critical evaluation, the number of hearing aid types was reduced from 33 to 23 when corresponding devices failed to match well with the degrees and types of hearing losses present. A further decrease in hearing aid types could not be achieved as a consequence of many being already end-prescribed. Insufficiencies (n = 222) were found in 60% of the hearing aid evaluations: 59% involved dynamic hearing aid adjustments requiring better amplification (37%), distortion (18%) and dynamics (4%). Additionally, 16% affected hearing aid function and another 16% form (9%) and material (4%) of the otoplasty and the tube (3%). The last 9% of the deficiencies concerned the potentiometer cap: it hadn't been fitted in about half of the cases and had been lost in the other half despite being needed. Routine followup evaluations of the hearing aids occurred regularly in 76% of the cases with an effectiveness of 73%. Our results confirm the importance and necessity for pedaudiologic qualitative hearing aid controls in children.

聴覚の周波数分解能と時間分解能に着目したディジタル補聴器の評価

聴覚の周波数分解能と時間分解能に着目したディジタル補聴器の評価

聴覚障害幼児における補聴の評価の観点

聴覚障害幼児における補聴の評価の観点

Effects of acclimatization and deprivation on non-speech auditory abilities.

This article reviews the evidence for acclimatization and deprivation with respect to non-speech auditory abilities. Although this subject has not been studied extensively, clear evidence exists for acclimatization and/or deprivation effects on intensity discrimination, binaural masking level difference, and auditory localization and lateralization. There is also some argument for such effects with regard to changes in tolerance for intense sounds or preferred levels of amplification. However, the main evidence for these effects, changes in loudness discomfort levels with repeated testing, may reasonably be explained as procedural or task-related effects rather than changes in auditory abilities. On the other hand, the successful use of tinnitus maskers to treat hyperacusis suggests that particularly low tolerance levels may be improved by exposure to certain types of auditory stimulation. Overall, this retrospective review of changes in non-speech auditory abilities, associated with the presence or absence of listening experience, indicates that acclimatization or deprivation effects may have influenced the results of some of the experiments reviewed. This suggests that experiments designed to study acclimatization or deprivation are timely and useful. In addition, acclimatization and deprivation are potential variables that should be considered, and preferably controlled, within experiments on auditory abilities. Clinically, the review adds weight to the argument for considering acclimatization and/or deprivation in hearing aid fitting and evaluation.

A method for analyzing rating scale data.

Subjective ratings are often used in the evaluation of hearing aids, loudspeakers, speech processors, and other systems involving sensory stimuli. The analysis of rating data, however, presents problems since the usual parametric assumptions underlying standard statistical techniques (e.g., t tests, analysis of variance) are not applicable to subjective ratings. A nonparametric method of analyzing rating data is described using concepts derived from signal detection theory. In order to compare two sets of ratings, a nonparametric estimate of the area under the ROC curve is obtained by first deriving the correlation function relating the two sets of ratings and then summing over half the range of the correlation function. This statistic, the half summed correlation (HSC), is relatively easy to compute and can be used to test, with known statistical power, for various differences between two sets of ratings (mean differences, variance differences, mean plus variance differences). It is also possible to rank sets of ratings using this statistic and to apply various multidimensional techniques designed for ordinal data. A variation of the analysis of proximities using HSC’s will also be described. [Work supported by NIDCD.]

雑音負荷時の語音了解度によるプログラマブル補聴器の比較

雑音負荷時の語音了解度によるプログラマブル補聴器の比較

Hearing Aid Selection and Evaluation for Pre‐school Children

It is chiefly in schools for the deaf, kindergartens for the hard of hearing, and other facilities where hearing aids are fitted to children in Japan. Persons in charge of hearing aids in each school or facility, execute fitting to their own opinions, without a standard method of fitting. However, it is the general view that children should wear hearing aids regardless of hearing level and that they should learn to use their ears. In this paper, I described the fitting method in Japan. In addition, I explained in detail the fitting method that considers the functional gain which is becoming the main measurement, and introduce examples. I also explain that the effect of the hearing aid is measured by the functional gain, without the measure of insertion gain in Japan.

補聴器評価のための擬似音場検査システムの開発 その２ ＫＥＭＡＲによる音響的検討

補聴器評価のための擬似音場検査システムの開発 その２ ＫＥＭＡＲによる音響的検討