To determine the suitable mapping after cochlear implantation for young children, we have studied six patients who have been operated on in the Kyoto University Hospital. Five of the patients had congenital deafness and one perilingually deafness. Four children with congenital deafness covered their eyes with their hands or closed their eyes at C level measurment of the first mapping session. It was considered that they confused the sound stimulation with the visual stimulation. As these four children refused the second mapping session the stimuli for C level measurment was excessive. At the first mapping session these four congenital deaf children took their parents hands or touched their cheek by their own hands just before they covered their eyes, and we thought that it has to be set as the C level. When the children use the speech processor for the first time after mapping, we set sensitivity level lower than the most suitable level. As they showed clearer responces to the sound, we could easily tune up the map.

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Pediatric audiometry was carried out in 96 children with normal development and hearing, aged 12 through 43 months. The distributions of auditory thresholds for four frequencies (0.5k, 1k, 2k and 4kHz) obtained from these children had a positive correlation with age, and were reduced as a function of age.
To define the normal limit of hearing level, we calculated the cumulative scores of thresholds obtained from each age group: 12-17 months, 18-23, 24-29, 30-35, and 36-43 months, The data analysis showed that the cumulative score of 85% in every threshold distribution correlated closely with changes in hearing level by age. From a practical point of view, it is useful to regard the hearing level that corresponds to the cumulative score of 85% in each age group as the normal limit of hearing level in each age group.

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Twenty cases, born during 1982-1997, of congenital hearing loss following maternal rubella are reported. The patients' mothers contracted rubella patients between the second and seventh months of gestation. Three cases were accompanied with persistent ductus arteriosus and cataract. The severity of deafness seemed to be correlated with the time of maternal rubella infection. Though most cases were children with bilateral hearing loss, some cases who suffered from rubella after the fourth month of gestation were those with asymmetry hearing loss, and three cases were those with unilateral hearing loss. These cases must be followed until their hearing abilities can be tested correctly. To protect children from congenital rubella syndrome, it is suggested that our rubella vaccine program should be conducted in order to prevent prevalence of rubella. Woman are advised to test their serum rubella antibodies and receive rubella vaccine before pregnancy.

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Objective: The purpose of this study was to describe the acoustical changes of quality of vowel and syllable in a child with Nucleus 22 cochlear implant, during 7 years from onset of deafness to 18 months after implantation. Design: 100 syllables were used as speech materials. Subjective and acoustic analysis were carried out on a subject. Results: 1) After implantation, the results showed improvements at the only F0 and F0 sway, but not for subjective analysis, F1/F2 pattern, F2 transition and voice onset time. Conclusions: 1) F0 might be improved easily so as to be basic stage. 2) At the point of articulation, there are problems that vowel especially, formant frequencies does not separate. Therefore, we should perform speech therapy, especially considering modulate tongue, articulation movements, regulate larynx movements, 3) Age of operation, use of hearing and speech therapy after deafness would reflect postoperative performance. 4) It should be necessary for us to make auditory device as soon as possible that hearing-impaired children did not make their articulation worse.

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The ototoxic side effect of the loop-diuretics was first reported by Maher in 1965. Since then, many cases have been repoted in the literature and the clinical features of these side effects have been clarified principally. On the otherhand, however, the audiological analysis of the hearing disturbances resulted from this side effect have not yet been performed.
The purpose of this paper is to review the clinical cases appeared in the literature with a special reference to the side effects on hearing and to discuss the principal features of this inner ear lesion.
In conclusion, the authors stated that the following five items were recognized for the special natures of this hearing disturbance. 1) acute development 2) binaural, sensorineural 3) good recovery 4) all frequency affection and 5) possible recurrence.

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We occluded the bilateral common carotid arteries of 4 rats as a model of brain death auditory brainstem responses (ABRs) were continuously recorded every hour using click stimulus in 4 rats more than 8 hours. And then, rats were perfused and the brain pathology was studied under light microscope. The results were that:
1) The amplitude of the P1 increased significantly.
2) All the peak latencies had no change.
3) The CA1 and CA4 regions of the hippocampus showed atrophic change and necrosis of neurons.
The increased amplitude of P1 which originates from the cochlear nerve and cochlear nucleus can be considered to be excited itself. But we supposed that according the pathology of the brain, during or following brief ischemia, CA1 and CA4 regions of the hippocampus showed atrophic changes, and necrosis of neurons. Then, extracellular glutamate concentration massively could increase, and cause disinhibition of the efferent nerve pathway of brain and/or the olivocochlear bundle, which could excite the cochlear nerve and cochlear nerve nucleus, and finally could increase the amplitude of P1.

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In 1739 patients who presented to Nagoya University Hospital between 1972 and 1998 within 2 weeks after the onset of unilateral sudden deafness, relationship between hearing recovery and tinnitus or ear obstruction feeling was investigated. 1542 patients (88.7%) had tinnitus and 833 patients (47.9%) had ear obstruction feeling. Of 197 patients without tinnitus, 124 patients (62.9%) had ear obstruction feeling; the proportion was significantly higher compared to 46.0% in patients with tinnitus. The initial hearing level in patients with tinnitus was worse than that in patients without tinnitus but the final hearing level was not different between patients with and without tinnitus. There were no significant differece in hearing recovery between patients with and without ear obstruction feeling.

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The Degital feedback suppresion (DFS) system to reduce acoustic feedback has been developed recently and was originally reported by Itami in 1992 in Japan. It was evaluated that how much hearing gain could be accessed by the elimination of the acoustic feedback as a result of the application of the DFS system. Fifteen profoundly head-of-hearing children whose auditory thresholds were beyond 90dB were selected, and mesurements on 26 ears were carried out. Median values of the auditory thresholds was 106.3dB. Functional insertion gain measured at 1, 2 and 4kHz was 10.5dB, 12.0dB and 19.2dB respectively.
Observation of the scene of aural comprehension showed improvement of the perception of environmental sounds distant from 1 to 2 meters and conversation.
Application of the DFS system for 6 months showed the increase of the amount of phonation and improvement of the intonation but speech discrimination by the developmental test.
There was no case that showed deterioration of hearing level using the DFS system. Application of the DFS system was valuable for the cases that could not obtain a sufficient hearing gain with traditional hearing aid.

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