Sequential recording of Electrocochleography (EcochG) and auditory brainstem response (ABR) on the same time axis were studied in five adults with normal hearing. EcochG was elicited by intratympanic recording. ABR was recorded by vertexmastoid lead. EcochG and ABR were recorded on the separate channels on the data recorder, and sequential recording was performed with off-time recording on Micro Vax II minicomputer. The results were as follows. 1) Sequential recording of EcochG and ABR provided us the auditory electro-physiological aspects at the level of the inner ear and brainstem. And this technic will able to show us the auditory electro-physiological aspects at the level of the auditory pathway. 2) The sequential recording was possible to indicate the ABR correctly by using the N1 of EcochG instead of wave I of ABR.
When the tympanic membrane (TM) is perforated by trauma or otitis media, hearing threshold rises. Although the dynamic behavior of the middle ear with TM perforation is expected to be different from that with a normal TM, that with TM perforation has not been well analyzed. Therefore, in this paper, first, applying our own finite-element method (FEM) program, a three-dimensional FEM model of the human middle ear with TM perforation was established. Then, using this model, the dynamic behavior of the TM and ossicles was analyzed. Results are as follows: The effect of the TM perforation on the vibration patterns of the TM and ossicles depended on location and size of the TM perforation, the maximum decrease of the sound pressure in the cochlear was about 15dB. Therefore, a large hearing loss detected in clinical study would be caused by the cancellation effect in the cochlear or the middle ear pathology except for the TM perforation.
The threshold and the latency of the evoked otoacoustic emission (EOAE) in normal hearing subjects were studied and gender, laterality and reproducibility were discussed. The subjects were 14 volunteers (6 male and 8 female), and 28 ears with normal hearing were examined. The mean age was 24.5±1.9 years old (male 25.3±2.3; female 23.9±1.4). Short tone bursts (3ms of duration) of 1kHz, 1.2kHz, 1.4kHz, 1.6kHz, 1.8kHz and 2kHz were used to obtain EOAE from the acoustic probe N-1 (Cortiton Co.). The analyzing time was 20ms and the low cut filter was set at 200Hz and the high cut filter was set at 3kHz. Visual detection threshold was determined by 3 physicians and the latency was measured from the starting point of stimulus to the peak of the wave which was used for detecting threshold. There were no sex difference except the threshold of 2kHz, no laterality but very good reproducibility. No significant difference was observed between thresholds of each stimulus frequency, but significant difference on the latency. The stimulus frequency became higher, the latency became shorter. There was 2.4ms difference between stimulus of 1kHz and 2kHz.
Previous studies showed that a contralateral acoustic stimulation induces the amplitude reduction effect in the 2f1-f2 distortion products (DPOAEs). And it is well accepted that this contralateral DPOAE suppression is due to an action of the olivocochlear efferent system. However, the clinical utility of the suppressive effect of a contralateral sound is unclear. We investigated the contralateral auditory stimulation effect and a test/retest reliability on DPOAEs recorded in humans with normal hearing. Under a relatively stable test condition, the repeatability of DPOAE measurement seemed to be high enough to prove the existence of contralateral DPOAE suppression. Although some technical problems still remain, the contralateral suppression is expected to provide the informations of the olivocochlear system functioning in humans.
The aims of the present study is to confirm the reliability and the validity of the Japanese version of the Hearing Disability and Handicap Scale (HDHS) translated by the authors, and to investigate the availability of HDHS. The questionnaire was completed by 85 workers with a compensable noise-induced hearing loss. Scores of three subscales regarding the hearing disability and handicap increased with the elevation of averaged hearing levels in each subject. Chronbach's alpha coefficients for three subscales ranged from 0.84 to 0.93, which were at a stasisfying level. Factor analysis suggested that 20 items were categorized into 4 factors, F1: handicaps, F2: enjoying TV and radio, F3: detecting signal and F4: communication in daily life. It was considered that the Japanese version of HDHS can be an effective tool to assess the nature and magnitude of communication disorders in relation to the QOL in workers with noise-induced hearing loss.
Spectra 22 is a new portable speech processor which has been developed in 1994 for the users of a multiple electrode cochlear implant. In this strategy, 20 programmable filters are repeatedly scanned at an average rate of 250Hz, and up to 10 spectral maxima may be selected for the incoming speech signal. A comparison of speech perception in Japanese was performed between patients using the MPEAK and those using the SPEAK coding strategies. The study was undertaken in 15 postlinguistically deaf patients with electrical stimulations alone. The results show that the performance of patients using the SPEAK was significantly better than that of patients using the MPEAK in the recognition of closed-set vowels and consonants, open-set monosyllable, words and sentences in noisy condition.