Hearing Aid Fitting Procedures Research Articles

Lipreading with auditory low-frequency information. Contextual constraints.

The present experimental study investigated potential relations among three variables: (1) an audiovisual speech signal (i.e., low-frequency supplemented lipreading as opposed to pure lipreading), (2) typical, as opposed to atypical, sentences in a particular script (e.g., in a restaurant), and (3) the presence/absence of additional context (in the particular script) in 60 normal hearing subjects. All three variables revealed significant main effects, but no interactions were observed. The general facilitatory effect for the audiovisual signal is in line with previous research, but this effect was relatively weak compared to the main effect of typicality, which relies on cognitive activation of scripts. In a separate analysis, the typicality variable was also the only variable that interacted significantly with speechreading skill, typical sentences being perceived relatively easier by the skilled as opposed to the less skilled individual. The clinical implications of cognitive factors in hearing-aid fitting procedures, the construction of speech materials, and selection of individuals for rehabilitation were discussed.

Present Audiological Issues in the Education of Hearing‐impaired Children in Japan

This paper gives an overview of hearing aid fitting procedures and auditory (re)habilitation for hearing‐impaired children in Japan. The paper also reviews issues of audiological management in Japanese schools for the deaf and special classes for the hard‐of‐hearing and considers two kinds of simplified word discrimination tests (Japanese Auditory Number Tests and The Japanese Family Terms Discrimination Test). The paper also highlights several controversies between different institutions of thought and different methods of education of young hearing‐impaired children using conventional hearing aids and cochlear implants.

Rationale for the use of hearing-aid fitting procedures

Rationale for the use of hearing-aid fitting procedures

Harmonic Distortion Measurements in Clinical Hearing Aid FittingPreliminary Report

Measurement of the distortion from hearing aids and its influence on their fitting has become practicable with the implementation of real ear measurement in the audiological clinic. Thus the harmonic distortion measured in the ear fitted with the hearing aid can be measured by means of a probe in the ear canal. The objective of the present investigation was to examine the value of harmonic distortion measurements in the fitting of hearing aids within a clinical setting. The material comprised 101 consecutive patients who had been prescribed different types of hearing aids based on the POGO formula, using insertion gain measurements. 160 hearing aids were fitted and with the fitting strategy used, a distortion less than 10% was indicated in 122 fittings (76%), a distortion between 10 and 20% in 30 fittings (19%) and finally a distortion greater than 20% in 8 fittings (5%). In the cases with the distortion greater than 10%, the hearing aid setting was maintained and the magnitude of the harmonic distortion was controlled with a 2-cc coupler. At the hearing aid fitting, the audiology technician can listen to the signal at the patient's drum and thus may hear distortion products. The relationship between the 'distortion' heard by the audiology technician and the 'distortion' heard by the patient was fairly good. Based on these preliminary findings it is concluded that harmonic distortion measurements may prove useful in the hearing aid fitting procedure.

Comfortable Loudness Level

This paper reports the results of a series of investigations of comfortable loudness levels with particular reference to their application to hearing aid gain prescriptions. Experiment 1 studied the effects of several stimulus waveforms, bandwidths, and durations on comfortable loudness levels for normal and hearing impaired listeners. Speech band comfort levels were found to be significantly higher than equal-duration noise band or warble tone comfort levels. Comfortable loudness levels were found to be independent of warble tone modulation parameters and of stimulus bandwidth (stimuli did not exceed critical bandwidths). In Experiment 2, reliability of comfortable loudness levels was evaluated in hearing-impaired subjects over two consecutive 1-year periods. Results indicated that comfortable loudness levels were slightly less reliable than thresholds. In addition, the results were consistent with a hypothesis that exposure to amplified sound produces a small increase in comfortable loudness levels. In Experiment 3, data from 67 hearing-impaired subjects were used to develop regression equations for prediction of comfortable loudness levels. Thresholds at the test frequencies were combined with comfortable loudness data at 500 Hz and 4,000 Hz. The prediction method was then evaluated using a new group of 25 subjects. Accuracy of predictions of comfort levels was substantially better with the new method than with an older method that relied exclusively on threshold data. Relevance of the outcomes to hearing aid fitting procedures is discussed.

The effect of interaural electroacoustic hearing aid properties on sound localization abilities in normal and hearing‐impaired listeners

The use and benefit of binaural amplification in the hearing impaired has generated considerable conflict. One easily measured benefit of binaural hearing includes improved sound localization. The normal binaural auditory system has the capacity to determine with considerable accuracy the azimuth of a sound source. Binaural hearing aid fitting procedures are typically accomplished with an independent concern for each ear. The interaural intensity, phase characteristics, and time of arrival cues processed by hearing aids undoubtedly affect the quality of the binaural fitting, The purpose of this study was to investigate the dependence between binaural hearing aids and in their electroacoustic functioning by determining minimal audible angles (MAA) and center position (CP) shifts in a sound localization task. Six normal and two hearing‐impaired adults responded to tonal and click stimuli using four selected pairs of hearing aids. These pairs were selected for matched electroacoustic characteristics: interaural phase distortion, and interaural transient distortion. Results of this study revealed smaller MAAs and CP shifts with the hearing aid pair matched closely in electroacoustic characteristics, whereas dissimilar pairs had larger MAAs and greater CP shifts. The results of this study provide information concerning binaural interactions and hearing aid fitting procedures with implications for improved binaural hearing in the hearing impaired.