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PubMedDate not supplied

Hearing-aid-processed signals: a new approach.

A new protocol for obtaining and utilizing hearing-aid-processed signals in hearing aid research or hearing aid selection is described. Data are presented which illustrate the extent to which this procedure may be expected to result in a signal spectrum at the subject's eardrum which is the same as the spectrum the subject would have received if the hearing aid itself had been placed on his ear (a directly-aided situation). An earlier investigation by the authors indicated that the traditional protocol for the production and utilization of hearing-aid-processed signals results in substantial discrepancies between these two spectra. The data presented were obtained using the KEMAR as the subject with a Zwislocki coupler as the KEMAR's ear canal/eardrum. The discrepancy between directly-aided and hearing-aid-processed spectra was typically +/- 2 dB for ear-level hearing aids fitted using standard, vented, or open earmolds (in open earmold fittings only the amplified component of the directly-aided spectrum is reproduced).

Acoustic Stimulation↗

PubMed1978

Methods for the evaluation of hearing aids.

Methods of hearing-aid evaluation are sub-divided into four broad categories, prescriptive selective amplification, selection from a set of existing hearing aids, use of a fixed frequency-gain characteristic, and adaptive fitting of a master hearing aid. The advantages, disadvantages, and controversies associated with each approach are reviewed and major research needs are discussed in the light of this review. Among the more important research needs are i) the development of improved speech tests that have low test-retest variability and which can discriminate between hearing aids with much greater precision than existing tests, ii) the development of reliable methods of predicting hearing-aid performance from audiological data, and iii) the determination of the optimum characteristics of the simplest, conventional hearing aid (i.e., a frequency-selective linear amplifier with no distortion other than peak clipping to limit maximum power output). It is also recommended that the simplest conventional hearing aid with gain, frequency-response, and clipping characteristics optimally matched to the subject's residual hearing be used as a reference for assessing more sophisticated hearing aids or alternative auditory prostheses for the hearing impaired. The third part of the paper provides a progress report on the development of a protocol for the prescriptive fitting of a wearable master hearing aid. The results to date show that the parameters of a conventional hearing aid can be adjusted according to well established optimization procedures so as to obtain superior, if not optimum, performance for each subject as a result of such individualized adjustments.

Acoustics↗

PubMedDate not supplied

Internal circuit noise of hearing aids and speech intelligibility.

The circuit noise generated internally by various components of a hearing aid is influenced mostly by circuit gain and frequency response. The measurement of this variable and its effect, if any, on the listener's ability to unders-and monosyllabic words through a hearing-aid system was investigated. The overall circuit noise of 10 behind-the-ear hearing aids of different brands with comparable gain and frequency response was measured. Based on these measurements, a low-noise and a high-noise hearing aid were selected as the test aids. The internal circuit noise of each test aid was then measured automatically by utilizing a 1/3-octave-band tracking filter. Monosyllabic words were recorded through the test aids at two gain settings. The prerecorded test tapes were presented to 32 normal-hearing listeners. Findings indicate that different amounts of circuit noise generated internally by a hearing aid do exist among various aids. However, the noise generated by the hearing aids used in this study does not affect significantly the intelligibility of monosyllabic words.

Hearing Aids↗

PubMed1977

A hearing aid malfunction detection unit.

A system is described, the Hearing Aid Malfunction Detection Unit (HAMDU), that electrically checks for proper operation of several aspects of hearing aid function. HAMDU is a miniature, add-on device which performs a check of hearing aid operation about every half hour, and which indicates malfunction by means of a highly visible, electrically tripped indicator. Functions checked include battery voltage, gain, distortion and noise, and continuity of the receiver cord. In addition, the indicator will be tripped if the hearing aid is turned off. HAMDU is small, low in cost, can be adapted to most body aids, and has no effect on hearing aid performance. The primary features of the system are that the hearing aid is checked periodically throughout its use, and the aid does not have to be removed from the wearer. The unit is designed specifically for body type hearing aids worn by children.

Electromagnetic Phenomena↗

PubMed1979

Hearing aids. A study of the performance capabilities of new instruments.

Evidence in the literature states that minimally 50% of the hearing aids that are worn by children are malfunctioning. The result is that these hearing aids are rejected by children who probably could benefit from amplification. This study shows that a large percentage of new hearing aids malfunction according to a number of specified parameters and points out the reasons for the malfunctioning. A cross-sectional sample of 14 manufacturers' hearing aid submissions (a total of 166 new aids) were comprehensively studied by the British Columbia Research and Development Laboratory, Victoria. Sixty-five percent of the hearing aids failed the primary and secondary criteria during the initial evaluation period. Results of this study provided valuable information to manufacturers of hearing aids and also to those who fit hearing aids with regard to improvements necessary to meet reasonable standards.

Hearing Aids↗

PubMed1975

Measuring in-the-ear gain of hearing aids by the acoustic reflex method.

The gain of hearing aids is conventionally measured in a hard-walled 2-cc coupler. It has become increasingly apparent, however, that many interacting variables can affect the aid's behavior in an individual ear quite significantly. Therefore it is desirable that any departure from coupler response be known. A number of methods have been used to measure real-ear gain, some of which require expensive or nonstandard instrumentation. An alternative method is described, based on measurements of aided and unaided acoustic reflect thresholds that appears to have certain advantages over other methods. Sound-field intra-aural reflex thresholds for six one-third-octave noise bands were determined for 20 subjects using a postauricular aid under three conditions--unaided, aided/ear occluded, and aided/ear nonoccluded. Real-ear gain was defined as the difference in decibels between aided and unaided thresholds. Results showed wide individual differences in real-ear response. Average occluded real-ear gain was about 5 dB greater at 1.6 k Hz, and about 5 dB less at 3.15 k Hz, than the gain in the artificial ear. When the aid was coupled to the open ear, average real-ear response was down at all frequencies relative to the 2-cc coupler, although relative to the closed-ear response frequencies above 1.6 k Hz were emphasized. It is argued that real-ear response can be expected to vary considerably depending on the location and orientation of the microphone of the aid on the head or body. It is suggested therefore that real-ear measurements be part of every aid selection procedure, especially for persons with a reduced dynamic range. Response modifications might then be possible to enable the critical speech frequencies to be heard at a comfortable level.

Adolescent↗

PubMedDate not supplied

The otolaryngologist and the hearing aid delivery system: current federal regulations.

New proposed rules and regulations concerning trade practices for the hearing aid industry have been developed in response to political pressures from Congress and consumer groups. Revisions to the trade regulations proposed by the Federal Trade Commission (FTC) include (1) more stringent limitations in advertising, (2) written permission to sell a hearing aid at home or in the buyer's place of business, and (3) the right of a buyer to cancel a hearing aid sale, rental, or lease within 30 days. Testimony on hearings regarding this rule are being reviewed by the FTC presiding officer. Food and Drug Administration national standards for the labeling and sale of hearing aids became effective Aug 15, 1977. A medical evaluation by a licensed physician is required before a hearing aid may be sold. Fully informed adults may request a waiver of this requirement for religious or personal beliefs, but a medical evaluation is mandatory for persons under 18 years of age. A User Instructional Brochure, which lists several conditions for which medical advice is advised, must be reviewed with the prospective buyer. In the recognition that some physicians may be dispensers of hearing aids, the Judicial Council of the American Medical Association has recommended that a physician may dispense hearing aids if it is in the best interest of the patient, but that a physician should not be encouraged to retail hearing aids in his office if other adequate community facilities exist.

Advertising↗

PubMed1978

The effect of hearing aid use on the user's residual hearing. A follow-up study.

This paper reports on a follow-up study into the effect of hearing aid amplification on the user's residual hearing. Four groups of deaf children; 18 in group A, 14 in group B, 15 in group C and 8 in group D were followed up for a period of four consecutive years. The children in group A and in group B were using monaural hearing aids throughout this period with maximum acoustic outputs ranging from 130-136 dB SPL and 116--128 dB SPL respectively. The children in group C were not using hearing aids during the first three years but during the fourth year they were monaurally fitted with similar hearing aids as those issued to children in group B. The children in group D were using binaural hearing aids during the first three years but in the fourth year they were restricted to only one hearing aid. The hearing aid levels of the children at 500, 1 000, 2 000 and 4 000 Hz were ascertained both at the beginning of the investigation, at subsequent 6-monthly intervals for the first three years and at the end of the fourth year. It was found that the hearing acuity of the hearing aided ears showed slight "improvement" during the investigation while the hearing acuity of the unaided ears showed slight "deterioration" in all frequencies tested.

Amplifiers, Electronic↗

PubMed1978

Requirements on speech processing hearing aids for the profoundly deaf, some preliminary remarks.

Many severely hard of hearing and profoundly deaf persons seem to get very little help from an ordinary hearing aid. This observation has prompted the development of tactile speech processing aids. These aids should however only be used if it can be shown that the subject has no useful residual hearing. In the case of a profound hearing loss the audiogram might in some cases show tactile sensations in the ear. To get a better estimation of the remaining auditory capacity experiments have been made with frequency discrimination measurements, and with speech tests consisting of rhyming word pairs. Results from these different tests are summarized in relation to an audiogram classification system. Two tactile speech processing aids are described. Evaluation studies with these aids show positive results but these results must be compared with the results that can be obtained with ordinary hearing aids and different types of auditory speech processing hearing aids. The possibility to use extreme auditory recording must also be studied. In this case the transmitted signal is not speech-like and it is possible that this limits their usefulness. Experiments with this type of aids might however give valuable information about how the human perceptual systems process signals derived from the original speech signal.

Audiometry↗

PubMedDate not supplied

Users' satisfaction with hearing aids.

Seventy-one hearing aid users were surveyed two years after their initial fitting to determine whether they (1) wore the hearing aid(s) prescribed, (2) were satisfied with their aid(s), (3) had specific complaints about their aid(s), and (4) would recommend that a hearing-impaired friend or relative go through the same hearing aid selection process. Ninety-six percent of the respondents obtained that aid that we recommended. Eighty-eight percent were "very satisfied" or "satisfied" with the help that their aid(s) provided. Eighty-two percent would recommend that a hearing-impaired friend or relative go directly to a "hearing specialist" for assistance when selecting a hearing aid.

Consumer Behavior↗

PubMed1979

The role of communication aids in the rehabilitation of hearing impairment.

The primary emphasis in rehabilitating the hearing impaired has involved fitting a hearing aid. There are patients however, who can be helped by communication aids in addition to, or in place of hearing aids. Communication aids include any device, other than a conventional hearing aid, which assists the hearing impaired in maintaining contact wiht the normally hearing. In Scandinavian countries a sophisticated system for rehabilitating the hearing impaired has evolved and communication aids are recommended extensively. Similar aids exist in North America, but clinicians have not yet developed a full awareness of how these devices can benefit their patients. This paper represents the results of a two year survey undertaken to identify and evaluate various devices available in Toronto. The contribution these aids can offer in rehabilitating patients is discussed.

Amplifiers, Electronic↗

PubMed1979

First-aid preparedness in small workplaces with special reference to occupational health services.

First-aid preparedness was surveyed in 163 small firms employing 2,400 persons. Although 11% of the employees had received first-aid training, half of the firms lacked first-aiders. Only one-fourth of the first-aid kits were equipped according to instructions. Checking and maintenance of the equipment, as well as information about first aid at the place of work, were generally inadequate. Instructions were commonly lacking for the safe use of chemical substances. Only 9% of the firms fully complied with the requirements for optimum first-aid preparedness. Employers at small firms seem not to be sufficiently aware of their liabilities with regard to first aid. Yet, most of the faults and defects could be corrected by means of arrangements within the firms once the instructions were better known. During their visits to places of work occupational health personnel should inspect the first-aid preparedness and advise the employer on first-aid requirements. In addition the expertise of the insurance company, the local Red Cross or the regional institute of occupational health may be utilized.

Finland↗

PubMedDate not supplied

Presbyacusis, hearing aids and aging.

This paper considers the factors of presbyacusis and age-related psychological changes in older adults in terms of their effects on the use or potential use of hearing aids as a means of improving aural communication. Data are presented on the prevalence of hearing impairment and the extent of hearing aid use in aging listeners. Four major classes of presbyacusis are described (sensory, neural, metabolic, and cochlear conduvtive) and a hearing aid prognosis is made for each type of disorder. It is shown that aging produces deficits in pure-tone thresholds, the speech reception threshold, and speech discrimination, but not all losses can be 'corrected' with a hearing aid. Binaural (stereophonic) devices are psychoacoustically superior to monaural devices; however, behavioral and personality changes in older patients often create problems of adaptation to the binaural aid. These changes may also affect the fitting of an aid and the patient's ability to learn to use it. Some practical suggestions are offered on the evaluation of hearing aids and it is emphasized that adequate orientation and counseling are typically required if hearing aid treatment is to be successful in presbyacusis.

Adaptation, Psychological↗

PubMed1992

CSF in 85 patients with AIDS and CNS cryptococcosis.

In an eight years time period (July 1984-June 1992) CSF samples of 40718 patients were studied, and 610 were from patients with AIDS clinically diagnosed and immunologically confirmed through HIV antibodies detection. Among opportunistic infections detected in them 85 were CNS cryptococcosis. For the purpose of this study the CSF of these 85 patients are the AIDS group of CNS cryptococcosis. For comparison, CSF data from 50 patients with CNS cryptococcosis but without AIDS were taken (non-AIDS group); in this group, 22 patients were immunosuppressed after renal transplant. In AIDS group, the more frequent CSF findings were: yeast presence at direct exam (Fuchs-Rosenthal cell counting chamber), growing of the yeast in cultures, and gamma globulins increase. In non-AIDS group were more frequent: hypercytosis, neutrophil cells presence, and total protein increase. Differences between the two groups are discussed taking into account CNS/CSF immune changes induced by HIV infection. It is concluded that in CNS cryptococcosis of patients with AIDS the CSF evidenced more extensive signs of the fungal opportunistic infection than signs of inflammatory response to the infection. The latter were more prominent among patients of the non-AIDS group of CNS cryptococcosis.

Acquired Immunodeficiency Syndrome↗

PubMed2026

Utility of hearing aid use on neurocognitive functions and auditory processing: A systematic review.

PURPOSE: Hearing loss not only affects the peripheral auditory system but also leads to changes in central auditory pathways and neurocognitive skills. The use of hearing aids has shown potential benefits in mitigating the adverse effects of hearing loss. Earlier literature showed various studies assessing the impact of hearing aid use on cognitive functions and auditory processing, a comprehensive review of the existing literature is warranted. Existing literature showed heterogeneous outcomes among studies investigated the effect of Hearing aid use in combating the adverse effects of hearing loss on neurocognitive functions and auditory processing. METHOD: Databases including PubMed, SciELO, Cochrane Library, PsycINFO, Web of Science, and Index Copernicus were searched (2005-2025) using English keywords on hearing aid effects on neurocognition and auditory processing in individuals with hearing loss. Studies on effect of hearing aid use on neurocognition and auditory processing were included, while those involving cochlear implant users or other neurological disorders unrelated to hearing loss were excluded. Titles, authors and publication years were examined, and duplicates were removed. RESULTS: Total of 61 research papers were found on specific area and were included in the present review. Findings of these 61 articles have been analysed and are reported in this article. The outcome of the present study showed usefulness of hearing aid use on neurocognitive functions and auditory processing. CONCLUSION: The present literature review emphasized the importance of early rehabilitation through hearing aid use to alleviate the adverse effects of hearing loss on neurocognitive function and auditory processing.

Humans↗

PubMed1978

Hearing aid evaluations for persons with total postlingual hearing loss.

To answer the question whether persons with total postlingual hearing loss can benefit from hearing aid use, hearing aid evaluations were carried out for 18 subjects. Nonstandardized listening tasks were necessitated because none of the subjects could discriminate speech. Subjective considerations played an integral role in the evaluation procedure. The results of the evaluations were as follows: (1) six subjects became new hearing aid users; (2) two retained the aids they were already wearing; (3) one improved when the hearing aid was changed to the opposite ear; (4) one obtained a satisfactory replacement for an inadequate instrument; and (5) eight were unable to use an aid to advantage. Thus, it is important that all persons with total postlingual hearing loss be afforded the opportunity of a careful hearing aid evaluation.

Adult↗

PubMed1978

Factors influencing use of hearing aids.

A follow-up questionnaire was mailed to new hearing aid users. The questionnaire responses of 430 persons, 73% of the sample, were related to age, audiometric, and hearing aid evaluation data obtained at the time of fitting. Reported usage of the aids was also analyzed in terms of the type of fitting and according to length of postfitting training. Further, the reasons for limited or nonuse were tabulated. The population in the present study, in comparison with that of previous investigations, was characterized by relatively young age and predominantly noise-induced, sensorineural type hearing loss, with mild hearing loss for speech; these factors led to a high proportion of selective amplification fittings. Reported overall use did not differ among the types of aids. Overall use declined with increasing age, and the majority of persons in this population used their aids selectively rather than on a full-time basis. Length of postfitting training appeared to increase hearing aid use. Mean audiometric and hearing aid evaluation data remained relatively constant across four usage categories: "always," "often," "occasionally," and "never." Excessive background noise and lack of need constituted 63% of the reasons given for limited use or nonuse.

Adult↗

PubMed1978

Evaluation of hearing aid fitting based on the patients' experiences from everyday listening conditions.

We found that a relationship existed between degree of sensorineural hearing loss and discrimination score obtained in free field with convenient hearing aids against background noise. However, the standard deviation was so great that we could not elaborate a diagram from which, with any reasonable degree of accuracy the expected discrimination score with suitable hearing aids could be predicted for each individual patient. Then 20 patients with sensorineural hearing losses tried different hearing aids under everyday listening conditions, and simplified speech audiometry against background noise was performed. We found that none of the patients achieved better discrimination scores with aids they rejected under everyday listening conditions than with aids they preferred. This indicates that we need to pay attention to the patient's experience with hearing aids under everyday listening conditions in each individual case, when a hearing aid is to be selected.

Adult↗