26 children with hearing loss of 71-120dB were trained for more than three years by uni-sensory method by hearing, and were able to enter the ordinary elementary school. They were tested in VIQ, Japanese achievement, reading ability after nine years of age, and the relation between the grade of hearing loss, PIQ, starting age of training, training period in preschool years and the present language ability were investigated. The results were as follows; (1) 18 children (70%) with above 90 in VIQ at school age kept the same level. 8 children (30%) less than 89 in VIQ did not develop and some showed lower level. (2) 18 children (70%) with more than 90 in VIQ after nine years of age got a good mark in Japanese achievement test and reading ability test, but 8 children (30%) with less than 89 in VIQ got a bad mark. (3) Language ability at school age closely related to the mark of VIQ after nine years of age. Efficient preschool training was indispensable in order to keep the high mark of VIQ after nine years of age. (4) The grade of hearing loss, PIQ, the starting age of training, training terms, added parents' direction, were concerned the development of VIQ at school age. Profound hearing loss and low mark of PIQ, training start after two years and seven months old, preschool training terms for shorter than four years, poor direction of parents inclined to get the low mark of VIQ.
The effect of hypothermic condition upon ECochG and ABR was examined in 10 children with congenital heart anomalies. The age of children was ranged 11 months to 9 years old, and they underwent open heart surgeries under hypothermic anesthesia. The entire body was cooled to about 21°C over a period of 1 hour by the surface cooling method. After completion of their open heart surgeries, the patients were rewarmed to normothermia. The responses to click of 115dB SPL were recorded one day before the surgery and during the period of cooling and rewarming. As the temperature was going down, the latencies of N1 (wave I), wave III and V were linearly increased, and the increase rates in average were 0.11, 0.25 and 0.43msec/°C in wave I. II and V, respectively. The wave III and V were no longer present around 24°C but N1 disappeared at the lower temperature by 1 to 2°C. The SP was the most resistant to hypothermic condition and was recorded throughout the observation. The most interesting phenomenon in this study was the temporary increase in N1 amplitude which reached the peak value at 30°C and was reduced thereafter. At the time of rewarming, SP reappeared first and was followed by N1, and finally the wave III and V reappeared. The results obtained in the present study indicate that the brainstem in the most sensitive to hypothermia, followed by the cochlear nerve and the sensory hair cells are the most resistant to hypothermic condition.
The authors have developed an automated computer-aided audiogram classification system which executes pattern recognition of the standard puretone air-conduction audiogram. The system is composed of a micro-processer, floppy disk drive units, graphic color display and printer. Data of various kinds of audiograms were stored in the floppy disk through the key-board. The microcomputer detected and retrieved the characteristics of plotting curve of hearing loss level at each frequency through artifical intelligence technique. The authors calculated the mean value of hearing level at each frequency of 3000 audiograms, and few characteristics of plotting curve pattern were decided. Each audiogram patterns were divided with some segments according to these characteristics. By using regression equation technique ao each segment, the computer-aided audiogram pattern classification procedure was established. The ability for plotting curve recognition and judgement of hearing level utilizing the computer showed no significant differences from those done by physicians. This new system can be effectively applied in screening audiometry and automated health testing.
Comparative studies between the right and left auditory evoked potentials with latencies from 50 to 70ms (positive peak) and from 90 to 110ms (negative peak) were made and significant difference was observed. Subjects were six normal Japanese. The amplitudes of the responses over the left temporal area were greater than the right for both natural and synthetic vowels, and the right ones were greater than the left for nonverbal mechanical sounds or harmonic distorted sounds such as pure tones, white noise, pulse waves and highly distorted natural vowels. These results suggested that the right hemisphere was dominant for the sound spectrum with harmonic relations whether the nature was verbal or nonverbal, and agreed with those of Tsunoda's using key-tapping method.
The origin of the negative EP (endocochlear potential) is still controversial. Some investigators believe that the negative EP does not exist in normal cochlea, but is produced by hair cells under such conditions as ischemia and ototoxic drugs administration. However, we do not agree with them in this respect of generation mechanism of the negative EP, and think that the negative EP exists under normal condition. The following data seem to lend a further support to our theory. 1) The maximum negativity of the EP produced by perilymphatic perfusion with ototoxic drugs is not different regardless which one of the perilymphatic spaces (the scala vestibuli or scala tympasi) is perfused. 2) Simultaneous perfusion in the scala tympani with control perilymph does not decrease the negativity of the EP attained by perfusion with the ototoxic drug in the scala vestibuli. 3) The elevation of PO2 in the scala tympani in the ischemic cochlea does not result in the increase of the EP.
By means of digital filtering technique, averaged auditory brainstem responses were devided into slow component with a frequency range of 50-300Hz and fast one with 400-1500Hz. Relationship between two components and stimulus intensity or interstimulus interval (ISI) was investigated. The slow component and wave V of the fast component showed almost the same latency change; a prolongation of the latency with decreasing stimulus intensity and ISI. As stimulus intensity was increased, the amplitude of wave V increased monotonically, while the slow component amplitude tended to level off at around 55-70dBSL. When stimulus interval decreased to 11ms, the amplitude of the wave V and the slow component decreased to approximately 75% and 90% of the amplitude at 125ms ISI. The slow component amplitude showed characteristic change to decreasing ISI; a marked increase at 25ms ISI and a slight decrease at 42ms ISI, these changes of the amplitude can be explained by superimposition and cancellation with Pa and Nb of middle latency response as seen in 40Hz event related potential designated by Galambos et al (1981). These results suggest that the two components of ABR are of different origins. The slow component seems to be generated through a pathway which is much more resistant to adaptation.
In our previous report, we studied on genetic analysis of 20 patients in 11 families with Pendred's syndrome reported in Japan, and the results showed similar trends of the coefficient of consanguinity of the parents, sex-ratio, segregation ratio, frequency of abnormal gene and incidence of this disease between our study and those found in the literature of the world. Moreover, we reviewed the literature, and the pathogenesis of deafness accompanied with goiter, pathohistological findings of the temporal bone, vestibular function, atypical cases of Pendred's syndrome and complications of this disease were also discussed.
The most suitable frequency response of hearing aids for moderate and moderately severe sensorineural hearing loss was studied in 164 subjects. The hearing levels of the subjects ranged from 40 to 85dB, and their audiograms were of flat or gradual-high-frequency-loss types. The subjects were classified into four groups according to their hearing levels and types of audiogram. The selection and adjustment of the hearing aid to each subject were performed in hearing aid clinic at our hospital. The most suitable frequency response was that with a low-frequency cut-off slope of 8-11dB/octave in all groups. On the other classification of the subjects by S. P. L. audiometry, the most suitable frequency response was the same in all groups. For adjustment of frequency response of a hearing aid to an individual case, it is appropriate to add a minimum modification to the value of 8-11dB/octave.
The simultaneous recording of the three kinds of auditory evoked responses (ABR, MLR, SVR) plotted on the logarithmic time scales was carried out in order to represent every component of these potentials without loosing each characteristics. From this logarithmic scale presentation of MLR, a new concept is obtained that the Po component of MLR largely depends upon the slow component of ABR, as being reported, and, at the same time the Pa and Pb components of MLR are identical to the P1 component of SVR. In other words, MLR should be described as the compound response of ABR and MLR.