A statistical study was made on 221 patients with hearing loss who visited our outpatients hearing aid clinic during the past five years between 1994 and 1998. A statistical analysis was performed for age, sex, the average of pure tone hearing level, configuration of pure tone audiogram, speech discrimination score, the correlation between electroacoustic characteristic of hearing aid and pure tone hearing level. 166 patients were indicated to use hearing aids. Their pure tone average hearing level was 57.2dB, and 75.7% of them had speech discrimination score more than 70%. In analysis of electroacoustic characteristic of hearing aids, the most frequently used gain and suitable maximum power output level (averaged in 500, 1000, 2000Hz) were correlated to the average hearing level. When the most frequently used gains were compared with gains calculated by half gain method, they were smaller than half gains in most cases. Additionally we investigated the correlation between age and the configuration of the hearing aid, the correlation between the social background of patients and indication to use hearing aids, and we made a comparative study of the patients using hearing aids in one ear and bilateral ear.
We sent out a questionnaire to investigate the situation of the specialized speech therapy institutes in the prefecture that conducting hearing tests and 3-year-old children health examinations. The results revealed that each institute has a different scientific environment and that there is a wide range of quality of tests and treatment among institutes. In order to properly diagnose hearing impairment at an early stage children, we must establish a system of examining 3-year-old children. Each institution must maintain the equipments. And technicians must develop their skills and establish a network for the exchange of informations and techniques.
Usher's syndrome is an autosomal recessive disorder characterized by congenital or progressive sensorineural hearing loss and vestibular dysfunction combined with retinitis pigmentosa. Of the various types of Usher's syndrome, type 1 presents with the most severe symptoms at a very young age. We report a case of cochlear implantation performed in a 9-year-old boy with Usher's syndrome type 1. It was noted that he had severe bilateral sensorineural hearing loss before the age of one and bilateral retinitis pigmentosa at the age of six. Although various types of hearing aids were tried after he was diagnosed as having severe hearing loss, none of them was effective. After cochlear implantation, he became able to hear environmental sounds and to recognize some words without lip reading. This suggests that for patients with Usher's syndrome type 1, cochlear implantation should be considered prior to the worsening of visual acuity in order to help them to live safely and to communicate with others.
Questionnaire studies were performed to investigate the efficacy of the use of hearing aids 100 questionnaires were collected out of 99 subjects in the study. The summary of the results was as follows. 1) The younger subjects were more satisfied with the use of a hearing aid than the older. 2) The subjects wearing a hearing aid for a long time are more satisfied with it. 3) The satisfactory order in the use of a hearing aid was behind the ear type (BTE)>in the ear type (ITE)>compeletely in the canal type (CIC); the larger one was more satisfactory. 4) K-amp types were more preferred in a calm place, on the other hand, digital types in background noise. In terms of music, linear and Kamp types were preferred. 5) The range of frequency threshold of a hearing aid worn by subjects, if possible, was measured to evaluate individual frequency gain among BTE, ITE, and CIC. No significant difference was found among them except the worse gain in the lower frequency of BTE. 6) The results of questionnaires suggest a direct correlation between the hearing aid gain of the subjects in the pure tone average and their hearing ability within a short distance.
Extra-cellar single unit responses to pure tone stimuli were obtained from the inferior colliculus of guinea pigs. Pure tone bursts of three different durations (100ms, 200ms, and 300ms) were used as stimuli and the effects of stimulus duration on the response properties were studied. Among 93 neurons sampled in this study, about 60% showed tonic responses to pure tone stimuli and about 30% showed phasic responses. Changing stimulus duration did not affect the response magnitude of all neurons exhibiting phasic responses to pure tone stimuli. However, some neurons exhibiting tonic responses showed the largest response magnitude to stimuli with the duration of 200ms. This result suggests that some neurons in inferior colliculus are tuned to stimulus durations.
To wear a hearing aid more easily, a new earmold for elderly hearing aid users was developed. Although they have taken the guidance for wearing a hearing aid and have been managed to wear it, it is a hard task for the elderly to wear a hearing aid by themselves. Loosing the elasticity of the ears of older people causes their ears to deform vertically. Also their finger tip creates a problem for them to rotate and insert the hearing aid at the same time. To ease these problems a new earmold which requires no rotation and can be inserted with one push, was developed. Twelve elderly people, averaging of age 85 (77-93 years old), were able to wear it without practice. Although they should recognize the structure of the external ear and the direction an earmold to fit, some people were able to insert the earmold with one finger and easily handled compared to the other types of earmold. There are three distinguishing characteristics for this new earmold. (1) After the profound understanding of the structure of elderly's external ear, the new type of earmold should be reshaped. The change of the shape makes an earmold to be inserted smoothly without rotation to the vertically-lined, non-elastic external ear. (2) By using the expandable material which transforms its shape with the ear temperature, the earmold slightly changes its shape after insertion. (3) The tip of the earmold should be extended to the second curve of the external ear. In future, this type of earmold appears to simplify the use of hearing aid for the elderly hearing aid users.
We performed inquiry, otoscopic examination, pure tone audiometry and speech discrimination test with word list 67-S for 69 subjects (over 60 years of age) who were found out some hearing impairment at automated multiphasic health examination. We evaluated hearing levels of 52 subjects (75.4%) who were diagnosed as having age-related hearing loss, and analyzed the association with smoking/drinking habits. The present study suggested that smoking habit was a risk factor for age-related hearing loss at low-tone frequencies, but drinking habit was not significantly associated with age-related hearing loss.