摘要:

Digital filters have been proposed by many authors for analysis and enhancement of the auditory brain stem response and related potentials. Because these techniques are unfamiliar to many, and require attention to underlying assumptions, an overview of the field is presented, with emphasis on limitations and risks of each method. Topics include Fourier transforms, finite impulse response (convolutional) filters, and infinite impulse response (recursive) filters.

ISSN:0196-0202    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The study consisted of two experiments on the insertion gain measured with probe tube microphones. In experiment I, the insertion gain of the same mild gain hearing aid was measured twice on 12 subjects using three commercially available probe tube systems. Test-retest measurements were made by two different examiners. Mean test-retest differences were all less than 4 dB with 95% critical differences for these measures varying from approximately 3 to 8 dB depending upon the test system used. In experiment II, the three sets of probe tube measures of insertion gain were compared to behaviorally measured functional gain in 7 hearing-impaired subjects at several frequencies. There were no significant differences among the probe tube measures of insertion gain or between these measures and functional gain. Functional gain was significantly correlated with probe tube insertion gain for each device at frequencies from 500 through 4000 Hz.

ISSN:0196-0202    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The negative attitude elicited by the presence of a hearing aid has been termed the “hearing aid effect.” The purpose of this study was to examine the negative reactions associated with hearing aids among new hearing aid users themselves and their perception of the hearing aid effect in their immediate environment. This was accomplished through a questionnaire completed just prior to hearing aid fitting and again 6 months after initial use of amplification. The responses to the questionnaires were compared between individuals who had chosen either in the ear or behind the ear type hearing aids, and between those using either monaural or binaural instruments. The effect of age on the data was also examined. The results indicated that the hearing aid effect was not expected or perceived very widely among these subjects, as only about 10% of them reported sensing negative attitudes to the use of hearing aids. Positive responses to the benefits of hearing aid use from other people often fell short of expectations.

ISSN:0196-0202    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

The response of a hearing aid depends on the design of the instrument and on the characteristics of the individual ear. In this paper a computer simulation of an in the ear (ITE) hearing aid is used to determine the effects on the hearing aid response caused by variations in the size of the ear canal, the magnitude of the eardrum impedance, and the vent size and damping. The simulation results indicate that, for an unvented hearing aid, changes in the size of the ear canal or the eardrum impedance shift the average sound pressure level at the eardrum but have relatively small effects on the overall shape of the frequency response. A vented instrument presents a more complicated situation since the vent modifies the low-frequency response in a predictable manner but can have unexpectedly pronounced effects at high frequencies due to the acoustic feedback.

ISSN:0196-0202    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Loudness discomfort levels (LDLs) traditionally have been used to set the saturation sound pressure level (SSPL) or maximum output of a hearing aid. Many procedures have been used to obtain LDLs for adults; however, no systematic study has been conducted to determine if LDLs could be obtained reliably for children. In the present study, LDLs were measured on 20 hearing-impaired children aged 7 to 14 years using a modification of a procedure described by Hawkins, Walden. Montgomery, and Prosek (Ear Hear 1987; 8: 162–169). Test-retest reliability measures were obtained for 8 of the 20 children, and this modified procedure was found to provide reasonably reliable results. Data from the group of 20 children also were compared with similar data obtained from 20 hearing-impaired adults. These results revealed no systematic differences in LDLs between the two groups, suggesting no a priori reason to limit the maximum output of a hearing aid for a child in this age range below the levels that are appropriate for adults. Poor correlation between LDLs and hearing levels for both age groups indicate a need for determining LDLs on an individual basis whenever possible.

ISSN:0196-0202    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Two case reports are presented to highlight the important effects of body temperature in clinical auditory brain stem response (ABR) measurement. Case 1 is an 11 year old boy in coma secondary to severe head injury. High dose barbiturate therapy suppressed brain stem neurologic signs and the ABR was relied on as a monitor of CNS status. Hypothermia during this period of intensive care was a crucial factor for meaningful interpretation of ABR findings. The second case was a 26 year old male undergoing hyperthermic therapy for advanced cancer. As body temperature increased from 38 to 42 degrees Centigrade (107.6 degrees Fahrenheit), there was a systematic decrease in latency for waves III and V. An overall hyperthermia-related decrease in the wave I-V latency interval of 0.5 to 0.6 milliseconds was observed on two test dates. ABR results for these two cases are discussed in the context of basic knowledge on body temperature and auditory electrophysiology.

ISSN:0196-0202    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Auditory brain stem responses (ABR) were measured from graduates of an intensive care nursery using an insert earphone. Approximately 95% of all ears had click-evoked ABR thresholds of 30 dB nHL or less. Absolute latencies of waves I and V were within the range observed for a circumaural earphone, once the delay introduced by the insert earphone's sound delivery tube was taken into account. Finally, interpeak latency differences and interaural symmetry were comparable to values observed when a similar group of patients were tested with a circumaural earphone.

ISSN:0196-0202    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

Neuromagnetic responses to stimuli presented through a 4-channel cochlear prosthesis were recorded from a deaf subject. The topography of the responses agreed with activation of the supratemporal auditory cortex. The responses to tone pips, noise/square-wave sequences, and to intermittent frequency modulation of a continuous tone resembled those obtained from subjects with normal hearing, being consistent with the good performance of this subject with his implant.

ISSN:0196-0202    

出版商:OVID    

年代:1988

数据来源: OVID

摘要:

In an effort to better quantify audiometric results, audiograms were modeled with a hyperbolic tangent function of the form: t = a tanh [(f-c)/b] + d. where t = threshold and f = frequency. The parameters, a, b, c, and d, were determined for a specific audiogram via a least-squares nonlinear curve fitting technique. The parameters describe salient features of the audiogram. The point (c, d) is the midpoint of the sloping portion of the audiogram, while a and b describe the slope. Other features of the configuration can be described by combinations of the parameters. This approach quantifies the entire audiogram and allows simple correlations of routinely gathered clinical data. To demonstrate the application of the model, a small data set of 500 Hz ABR and behavioral thresholds recorded from 28 ears (23 subjects) was analyzed. The model showed that agreement between the thresholds varied with audiometric configuration.

ISSN:0196-0202    

出版商:OVID    

年代:1988

数据来源: OVID