The modality of wave VI & VII of auditory brainstem response (ABR) were studied. The response threshold of wave VI was 42dB above hearing level, and of wave VII was 60dB. The producibility of wave VI was 78% at 60dB above hearing level, and 90% at 80dB. The producibility of wave VII was 52% at 60 dB above hearing level, and 65% at 80dB. Mean peak latencies and those standard deviations (SD) of wave VI were 7.3±0.2msec (at 60dB avove hearing level) and 7.2±0.2msec (at 80dB). Of wave VII, 8.9±0.3msec (at 60dB) and 8.8±0.3msec (at 80dB). At 80dB above hearing level, inter-peak latencies (IPL) and those SDs of I-VI and III-VI were 5.5±0.2msec and 3.3±0.2msec I-VII and III-VII were 7.2±0.3msec and 5.1±0.3msec. SDs related with wave V were both 0.2msec (I-V, III-V). Wave VI is reliable enough to apply for the clinical usage as one of the parameters of ABR.
The standardized tinnitus test proposed by Tinnitus Study Group in 1984 presented 30 onomatopoeias and their corresponding frequency areas of pure tones and band noise of pure tone audiometer as an indicator to evaluate the pitch and the nature of tinnitus. In order to re-investigate the adequacy of these 30 onomatopoeias, we analysed the relationship between subjective expression with onomatopoeias and pitch of tinnitus simulated by pure tones and band noise of pure tone audiometer. The subject matter were 263 tinnitus ears without hearing loss or associated with cochlea; deafness. The results obtained were as follows; 1) A total of 41 onomatopoeias was used for the subjective expression of tinnitus. However, among these 41 onomatopoeias, only 17 (41.5%) had been presented in the standardized tinnitus test in 1984. 2) Six onomatopoeias had not been presented in the standardized tinnitus test in 1984 although their frequency in use was more than 2% in this study. 3) As far as the relationship between onomatopoeias and their corresponding frequency areas of pure tones and band noise was concerned, discrepancies between the results obtained in this study and the proposals by the standardized tinnitus test in 1984 were found in 11 onomatopoeias out of 17 (64.7%). Based upon these results, we concluded that onomatopoeias as an indicator to evaluate the pitch and the nature of tinnitus should be re-investigated.
Thirty-five multiply-handicapped children with a hearing impairment were fitted with hearing aids, and auditory behaviors and vocalization were investigated in the follow-up study. Seventeen children out of twenty-eight who were observed for more than six months demonstrated the fair or good effects of hearing aid use. The effects were evaluated as the appearance of responses to sounds or voices and changes in quality or quantity of vocalization. Five children who showed no improvement in their auditory behaviors had associated severe motor and mental retardation, and also epilepsy. Six children had difficulty with the fitting of hearing aids because they did not like ear molds to put on their ears. It is emphasized that early diagnosis of deafness and the early fitting of hearing aids in multiply-handicapped children are important for their language development, even if their neurological status is not good.
ABR and EOAE were measured in 12 infants whose age was ranged between 3 months and 4 years, and these results were dincussed. In EOAE measurements 1.5kHz short tone bursts (35dBnHL and -10dBnHL) was used for stimulating sound. The response was averaged 300 times and the noise was rejected by the artifact rejection system of signal processor. The existence of EOAE response was judged by the presence of the obvious peak in 8-10ms after stimulation, and the comparison was made between two responses on different stimulations. Five cases judged as normal hearing in ABR showed good responses in EOAEs on 35dBnHL stimulation, but 12 cases judged as severe hearing loss in ABR were detected no responses in EOAEs. EOAEs in infants can be measured by using a signal processor for ABR, and the measurement is easy and noninvasive. Moreover, EOAEs clearly responded to stimulating sounds. So it was strongly suggested that EOAE is suitable for detection of hearing impairment and is a useful auditory screening in infants.
Detectability, peak latencies, and IPL of negative components of ABR were studied. The subjects were 213 normal hearing adults. The results were as follows: 1. Negative peaks revealed high detectability as same as positive. 2. Each negative peak latency and their IPLs were stable even if the acoustic intensity was varied. 3. Fast negative components were much influenced by a slow component than fast positive components. 4. IPLs of negative peaks were stable as same as those of positive under a fixed filter band, and negative components were thought to be able to apply for the estimation of ABR.
We conducted the loudness balance test at 3 frequencies with the center at the pitch of tinnitus. The subjects were 68 tinnitus ears without hearing loss or associated with cochlear deafness, and their tinnitus pitch was simulated by pure tones. Results obtained were as follows; (1) There were no statistically significant differences among the values of loudness estimated at 3 test frequencies. (2) The values of loudness estimated at 3 test frequencies coincided in about 30% of the subjects. (3) The values of loudness estimated at neighboring 2 test frequencies coincided in about 50% of the subjects. (4) There was a slight negative correlation between the value of loudness and the hearing level at the pitch of tinnitus. (5) There was no clear correlation between the subjective scoring for loudness and the hearing level at the pitch of tinnitus. (6) There were positive correlations among the values of loudness estimated at 3 test frequencies. (7) Correlation coefficients were less than 0.260 between the subjective scoring for loudness and the values of loudness estimated at 3 test frequencies. (8) The optimal evaluating method of subjective scoring for loudness should be re-investigated.
Two different procedures, Hyde formulas (a single regression using broad-band noise, BBN for short, and a multiple regression using the BBN and 500Hz) and bivariate plotting (BP) method reported by Silman et al., used in predicting hearing level from the stapedial reflex (SR) threshold data were evaluated for 63 subjects with normal hearing and 66 with hearing-impaired ears. None of both predictors suggested by Hyde was accrurate for clinical use together with adults and children. With the BP method, no method accurately estimated magnitude of hearing loss while maintaining a high proportion of separation from normal hearing ears with the hearing-impaired on the basis of position on the bivariate graph. Consideration of these findings obtained by the BP method was particularly useful in identifing simulation in adults as well as functional defness in elder children.