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PubMedDate not supplied

Human auditory steady state potentials.

The auditory steady state potentials may be an important technique in objective audiometry. The effects of stimulus rate, intensity, and tonal frequency on these potentials were investigated using both signal averaging and on-line Fourier analysis. Stimulus presentation rates of 40 to 45/sec result in a 40 Hz sinusoidal response which is about twice the amplitude of the 10 and 60/sec responses. No significant effects of subject age or sex were seen. The 40/sec response shows a linear decrease in amplitude and a linear increase in latency when stimulus intensity is decreased from 90 to 20 dB normal hearing level. This response is recordable to within a few decibels of behavioral threshold. Stimuli of different tonal frequency give similar amplitude/rate functions, with absolute amplitude decreasing with increasing tonal frequency. Signal averaging and Fourier analysis provide nearly identical amplitude/rate, amplitude/intensity, and latency/intensity functions. Both methods of analysis may be used, therefore, to record the 40 Hz steady state potential. Fourier analysis, however, may be the faster and less expensive method. Furthermore, techniques ("zoom") are available with Fourier analysis to study the effects of varying stimulus parameters on-line with the Fourier analysis procedure.

Acoustic Stimulation↗
PubMedDate not supplied

Test-retest reliability of a forced-choice procedure for determining most comfortable loudness level for speech.

A new forced-choice procedure for measuring comfortable loudness for speech was evaluated on a group of 30 normal-hearing subjects. The test-retest reliability was determined for the forced-choice ascending and descending approach and found to be high (r = 0.83 and 0.84). Clinical reliability indicated that 80 to 83% of the subjects varied no more than 5 dB upon retest. In a second experimental session, comparisons between the forced-choice procedure and the method of limits (ascending and descending approaches) were evaluated on a group of 14 sensorineural subjects. Results indicated the forced-choice procedure eliminated the measurement differences found with the method of limits (ascending and descending approaches) and the forced-choice measurements remained stable across varying degrees and configurations of hearing loss. The procedure is fast, reliable, and has several advantages over the method of limits procedure.

Adult↗
PubMedDate not supplied

Group amplification in schools for the hearing impaired.

In the present field study, ambient noise levels and the status of group FM-wireless amplification systems were examined in 19 classrooms for the hearing impaired. Classroom noise was judged to be unacceptably high thus justifying the need for group amplification devices. Physical inspection of the group systems revealed defects in approximately one-half of the 28 teacher and 89 student amplification units. The electroacoustic measurements showed wide variability in performance among systems. There also appeared to be no systematic relationship between the degree of hearing loss of the children and the amount of unit gain being employed by each specific amplification system.

Amplifiers, Electronic↗
PubMedDate not supplied

Four spondee threshold procedures: a comparison.

Two ascending and two descending procedures were used to obtain spondee thresholds from normally hearing and sensorineural hearing impaired subjects. Minimal differences were found when comparisons of threshold were made among all four procedures. Results indicated slightly more sensitive thresholds when the descending procedures were used and slightly poorer pure-tone average and spondee threshold agreement. Test-retest reliability was good for all four procedures, but large differences existed among the procedures in the amount of time and in the number of words required to establish threshold. Advantages and clinical implications are discussed.

Adult↗
PubMedDate not supplied

The time course of the acoustic reflex.

The time course of the impedance changes caused by the contralateral acoustic reflex was investigated in five normal hearing, young adult subjects The acoustic reflex function was measured with equipment having a time constant of 15 milliseconds which permitted precise temporal measures. Temporal intervals from signal onset and termination to various portions of the acoustic reflex function were derived using an analysis procedure based on the slope function underlying the acoustic reflex response. These temporal intervals are related to physiological events underlying the acoustic reflex.

Acoustic Stimulation↗
PubMedDate not supplied

SSW test performance-intensity functions for hearing-impaired adults.

The present study investigated the effects of intensity on hearing-impaired adults' performance on the Staggered Spondaic Word (SSW) test. Fifteen adults having mild-to-moderate cochlear hearing losses were administered the 40-item SSW test which was subdivided into four groups of ten items each, and presented at different intensity levels (20, 30, 40, and 50 dB SL re the three-frequency, pure-tone average). Subjects' responses were used to generate performance-intensity functions. Scores were analyzed for overall, competing, and noncompeting conditions. No significant differences were found for these hearing-impaired listeners' performance for items presented at the standard 50 dB and those at the low sensation levels.

Adult↗
PubMedDate not supplied

Comparing normal hearing and hearing-impaired subject's performance on the Northwestern Auditory Test Number 6, California Consonant Test, and Pascoe's High-Frequency Word Test.

The Northwestern Auditory Test No. 6, the California Consonant Test, and Pascoe's High-Frequency Test were presented to two groups of listeners. One group consisted of 12 patients with normal hearing up to 2 kHz accompanied by a high-frequency loss. The second group consisted of persons with normal hearing. There were significant differences between the two groups of listeners in overall discrimination scores, among the four intensity levels (10, 20, 30, 40 dB) and the three speech discrimination tests. When the data from the hearing-impaired subjects were analyzed, it was found that these individuals obtained higher scores on the NU 6 material at 20, 30, and 40 dB SL when compared with the California Consonant Test and Pascoe's test. The results from the Newmann-Kuel multicomparison test indicated no statistical significance between the results of the California test and Pascoe's test; however, the distribution of scores at 40 dB was different. Results of this study suggested that the NU 6 test was not sufficiently sensitive to detect consonant confusions in individuals with high-frequency hearing loss.

Adult↗
PubMedDate not supplied

Stimulus, response, and state variables in the testing of neonates.

This paper endeavors to answer three closely related questions: What motor behavior displayed by an infant may be considered to be a response to acoustic stimulation? What acoustic phenomena elicit such behavior? Does responsiveness vary with postconceptual age? Review of our work over the past decade reveals that we know the answers to the first two questions, but not the third. Briefly, arousal responses (eye and limb movements) are reliably elicited by wideband signals but not by narrowband signals. However, there is still confusion about whether preterm infants are more or less responsive than full term infants.

Acoustic Stimulation↗
PubMedDate not supplied

Selecting amplification characteristics for young hearing-impaired children.

The task of selecting the electroacoustic characteristics of hearing aids for young hearing-impaired children continues to challenge many clinical audiologists. The rationale for a theoretically based approach to this problem is presented. Additionally, issues related to the choice of an idealized speech spectrum for a theoretical selection model are considered in relation to the acoustic environment and auditory needs of young hearing-impaired children. Finally, the preliminary version of a computer assisted speech spectrum approach, which facilitates the initial selection of frequency/gain and frequency/SSPL characteristics is presented.

Child, Preschool↗
PubMedDate not supplied

Comparison of the revised Hearing Performance Inventory with audiometric measures.

Hearing Performance Inventory scores were correlated with sensitivity, discrimination, and sensitivity + discrimination measures for 39 subjects with noise-induced hearing loss. The highest correlation obtained (0.67) was with monosyllabic speech discrimination in noise. However, there were not significant differences in correlations among the three types of audiometric measures. The audiometric variables accounted for less than half of the variance in Hearing Performance Inventory scores; therefore they are inadequate in predicting the amount of self-perceived hearing difficulties. The need for a variety of hearing handicap scales is discussed.

Adult↗
PubMed1986

The National Acoustic Laboratories' (NAL) new procedure for selecting the gain and frequency response of a hearing aid.

A new procedure is presented for selecting the gain and frequency response of a hearing aid from pure-tone thresholds. This was developed from research which showed that a previous procedure did not meet its aim of amplifying all frequency bands of speech to equal loudness but that frequency responses which did so were considerably more effective. Measurements of 30 sensorineurally hearing-impaired ears (27 subjects), together with data from other studies, were analyzed to determine the best formula for predicting the optimal frequency response, for each individual, from the audiogram. The analysis indicated that a flat audiogram would require a rising frequency response characteristic of about 8 dB/octave up to 1.25 kHz and thereafter a falling characteristic of about 2 dB/octave. Variations in audiogram slope required about one-third as much variation in response slope. Three frequency average (3FA) gain was calculated to equal the 3FA gain of the previous procedure. Forty-four subjects (67 aided ears) fitted by the new procedure were evaluated by paired comparison judgments of the intelligibility and pleasantness of speech. The prescribed frequency response was seldom inferior to, and usually better than, any of several variations having more, or less, low and/or high-frequency amplification. On the average, used gain was approximately equal to prescribed gain. It is concluded that the new formula should prescribe a near optimal frequency response with few exceptions.

Audiometry, Pure-Tone↗
PubMed1987

Description and validation of an LDL procedure designed to select SSPL90.

A new procedure is described for measuring loudness discomfort levels (LDLs) for the purpose of selecting SSPL90 characteristics of hearing aids. The person is seated in sound field wearing a high-output hearing aid (with a known amount of 2 cm3 coupler gain) connected to a personal earmold. The loudness of frequency-specific signals is rated from a series of loudness category descriptors. The LDL is defined in terms of SPL developed in a 2 cm3 coupler, thus making selection of SSPL90 from hearing aid specification sheets practical. Experiments on LDL stability over time and validation of the SSPL90 selection are reported.

Adult↗
PubMed1987

Insertion gain repeatability versus loudspeaker location: you want me to put my loudspeaker where?

The traditional 0 degree (straight-ahead) location of the loudspeaker during insertion gain measurements is a poor choice, based on theoretical considerations, from the standpoint of measurement repeatability. In a series of experiments, we were able to demonstrate that a location 45 degrees to the side, or 45 degrees up and 45 degrees to the side, provided a much more repeatable measurement of basically the same insertion gain response.

Acoustics↗
PubMed1987

Clinical ear canal probe tube measurements.

This paper describes a variety of areas in which ear canal probe tube microphone measurements can be useful to the audiologist. Areas such as measurement of hearing aid insertion gain to match some predetermined target levels, output sound pressure level in the ear canal (real ear SSPL90), and assessment of FM systems and FM system-hearing aid combinations are discussed. In addition, some variables affecting the accuracy of these measurements and the reliability will be discussed.

Acoustics↗
PubMed1988

Loudness discomfort levels in children.

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.

Adolescent↗
PubMed1988

Probe-tube microphone measures in hearing-impaired children and adults.

This study was designed to investigate the reliability of real-ear measurements of sound pressure level (SPL) and to compare these values with two coupler measures of SPL. A commercially available probe tube microphone system was used to measure real ear SPL in both children and adults. Test-retest reliability decreased as a function of frequency for both groups and, in general, was slightly poorer for the children. For both groups, coupler to real ear differences were larger for the 2 cm3 coupler than for the reduced volume coupler; however, no significant differences were observed between groups. In addition, a measure of ear canal volume was not found to be a good predictor of coupler to real ear discrepancies.

Adolescent↗
PubMed1989

Variability of most comfortable and uncomfortable loudness levels to speech stimuli in the hearing impaired.

Methods for determining hearing aid settings often incorporate measurements of most comfortable loudness (MCL) and uncomfortable loudness (UCL) levels. This study examined the variability of loudness measures and their correlation to threshold data, using speech stimuli presented to hearing-impaired subjects. MCLs, UCLs, speech reception, and speech detection thresholds were obtained from 50 subjects having sensorineural impairments. The stimuli were CID W-2 spondees spoken by three female clinicians. Three MCLs and UCLs were obtained within each session, using ascending runs and a closed-set response list. Fifteen subjects were retested twice over intervals ranging from a week to several months. Between-session variability for the loudness measurements was less than or equal to 10 dB across sessions and speakers for the majority of subjects, with a tendency for the MCL and UCL to increase slightly over time. Significant variability was attributed to the use of live-voice presentation by different clinicians. High positive correlation was found between threshold and loudness data for subjects with relatively flat audiometric configurations but not for subjects demonstrating sharply sloping hearing losses.

Adult↗
PubMed1989

Temporal summation of repetitive click stimuli.

Monaural loudness balances were performed by eight normal-hearing subjects to determine the effect of click repetition rate on loudness sensation. Click trains of 500 msec duration were matched in loudness to a standard 500 msec 1000 Hz tone burst presented at three reference loudness levels (70, 80, and 90 phons). Click trains were presented at repetition rates of 11, 31, 51, and 91 clicks per sec. It was found that click trains at faster repetition rates required lower intensities for judgments of equal loudness sensation. This finding was attributed to the process of temporal loudness summation. The magnitude and nature of the temporal summation process as well as the influence of the reference loudness level are discussed.

Acoustic Stimulation↗