Since 1966 hearing checkup has been carried out in Sendai-city. This paper reported the result gathered from data of hearing test in 1970, 1971 and 1972. Number of school children received screening test were 20, 959 in 1970, 21, 479 in 1971, and 22, 684 in 1972. The test was performed for first grade by audiologists and for third & fifth grade children by nursing teachers. As the result, there are an eminent difference in percentage of appearence for hearing children between first and third & fifth grade school children. (first grade: 3.21%, third grade: 1.24%, and fifth grade: 1.22%) This data indicates that the screening test must be done carefully.
Fifteen cases (group A) with excellent, and 15 cases (group B) with poor score, of discrimination for filtered speech were selected out of 49 cases (98 ears) whose hearing level was within 30 dB at the speech frequencies. Number of correct answer was recorded for each monosyllable speech sound. Monosyllables which showed good discrimination in group A and poor discrimination in group B were selected and listed. The new list consisted of seventeen 1, 700Hz-low-pass-filtered monosyllables and three 1, 200Hz-low-pass-filtered monosyllables. By computing the amount of information obtained by the new list and the correlations of the new and the 57 AB list it was found that the new list was more sensitive and useful for the diagnosis of hearing disorders than the 57-AB list.
Auditory screening test using words instead of pure tones was administered for pre-school children. Ten different words (ex. television, banana and so on) used in this study were considered to be familiar to children and were administered at the level of 30 dB. Children were instructed to repeat the word which they heard after each word was given. If a child could hear less than 7 words out of 10 correctly, he was screened. This screening test was applied to 2, 564 children whose age distribution was 3 to 6 year old (mostly 4 or 5). As the method of this test was simple enough for these children, all cases could be tested satisfactrily. Out of 2, 564 children, 83 cases (3.2%) were identified. Forty two of them took the close examination of pure tone audiometry at our suggestion. According to the results of the test, 31 ears (55.4%) out of 56 had hard of hearing at the level of 30 dBHL or more. On the other hand, 94 children (188 ears) who passed the verbal auditory screening were found that all of them had pure tone threshold below 25 dB. It is concluded that the present method is prevented “bypass” of children with hearing loss and considered as usefull for an auditory screening test for pre-school children.
It was studied the relation between haemodialysis and hearing disorders. In order to obtain the relation between renal failue and hearing losses, 19 patients with renal failure who had never had any illness which might cause hearing losses, were examined by pure tone audiometer. Ten out of 19 cases were perceptive deafness of 20dB-50dB in the high frequencies. Thus this hearing loss seemed due to renal failure. Immediately before and after haemodialysis, BUN, serum concentration of sodium, potassium were ex amined and at the same time pure-tone audiometry was done. The degrees of hearing loss were constant and in a few cases tinnitus appeared and disappeared soon after. Pure-tone audiometry of 41 patients with renal failure treated with haemodialysis was done every 3 months for 3 years. Only 3 out of 41 cases revealed hearing loss of both ears more than 30dB in 8, 000Hz. None of others showed any change of hearing during these 3 years. Thus it was thought that good control of heamodialysis was hard to cause hearing loss. Tinnitus and nose-bleeding were often found in the patients treated with haemodialysis. It was not clear the relation between tinnitus and nose-bleeding. But it was studied that tinnitus had good relation with osmotic pressure and anemia.
The basic principles of impedance audiometry were described and the possibilities of the diagnosis in conductive deafness without ear drum perforation were studied. Differential diagnosis of otosclerosis, ossicular dislocation and adhesive and exudative otitis media were possible by tympanometry and static compliance. When tympanometry and static compliance are within normal values in cases with conductive deafness showing normal ear drum, the diagnosis can be made by history, the presence of Carhart's notch and x-ray findings of the temporal bone. By applying this method in cases, in which the bone conduction level is difficult to obtain or the result of the test is hard to evaluate especially in young children, it is possible to make the differential diagnosis of conductive deafness from sensorineural hearing loss in certain cases, but it is not possible to make the diagnosis of mixed deafness.
By using impedance meter (Madsen ZO72), it was demonstrated that the measurement of stapedial reflex in sensorineural hearing loss is useful as an objective test of demonstrating the presence of recruitment. In retrocochlear deafness, stapedial reflex threshold is elevated in most cases to 15dB higher level than that in normal hearing subjects. In central lesions as sensory aphasia, temporal lobe tumor or pineal body tumor which might have not involved stapedial reflex arc, the stapedial reflex can be elicited at the same level as in normal hearing sub jests, while in the lesions of the stapedial reflex arc itself, the threshold of the reflex is within normal value or elevated either or both ears. Therefore, topical diagnosis in the central auditory pathways is possible in combination with other audiometric tests including distorted or non-distorted speech discrimination test, directional hearing test, Békésy audiometry, etc. In postoperative cases of posterior fossa tumor in which symmetrical hearing loss and positive recruitment is demonstrated by stapedial reflex threshold, SISI and uncomfortable level with the findings suggestive of retrocochlear lesions in other audiometric test, the probable occurrence of loudness recruitment in branin stem lesions as suggested by Dix et al was also confirmed.
Very slow frequency sweep (5 minutes and 40 seconds per 1 octave) was adopted in ordinary Békésy audiometry as a new method for detailed measurement of hearing threshold along the frequency scale. The purpcse of this paper is to ascertain the limitation of this method in the viewpoint of exact recording of the threshold curve. One hundred and three ears with high tone loss of abrupt or dip type were tested. As the result, it was observed that the correct threshold was obtained in 101 ears, and only two ears showed so sharp slope of the threshold curve that the trace coincided the maximum limit of this recording. Accodingly, it was concluded that the usefullness of this method was recognized.
Inner ear damage resulting from intratympanic application of 3', 4'-dideoxy kanamycin B chloramphenicol succinate, minocycline monohydrcchloride, predex (an ototopical applied drug Whick is contained fradiomycin) and gentamicin was studied experimentally in guinea pigs and squirrel monkeys. The inner ears were examined by light and electron microscopy. It was found that the drugs caused severe damage to the hair cells in the organ of Corti and vestibule as well as some damage to stria vascularis. These damages to the inner ears in guinea pigs were more severe than that in squirrel monkeys. These damages in the inner ear were considerably reduced by ototopically applied co-carboxylase. On the basis of the findings, the possible diffusion routes of the ototopically applied drugs in the inner ear fluid, the dangers arising from their topical use and it's prevention were discussed.