Electrocochleographic and immunohistological changes in guinea pigs immunized with type II collagen were still controversial. In this study, we used chronically implanted round window electrode which we have developed in recent years for the purpose of assessing time sequence studies. Abnormal changes in AP were demonstrated in number of animals which showed threshold elevation, decrease in amplitude, and H-pattern configuration of input-output curve. The pattern of AP changes were divided into three groups. AP changes which exhibited fluctuation of amplitude with time seemed to be reversible but those which exhibited progressive decrease in amplitude were irreversible. From those results, it is assumed that there may be a different immune reaction from animal to animal, and it is supposed that abnormal autoimmune response may be one of the causes for the development of sensorineural hearing loss. In conclusion, we supposed that autoimmune responses may play an important role in inner ear diseases.
EOAEs and DPOAEs were recorded in 5 patients with idiopathic sudden deafness by use of ILO88 and ILO92 Otodynamic Analyser. In all patients hearing thresholds returned to normal or nearly normal after treatment. In 4 patients recoveries of EOAEs and DPOAEs paralleled with those of hearing thresholds. In one case, EOAE and DPOAE were detected when the hearing threshold of 4 frequencies (500, 1000, 2000, 4000Hz) were 55dB or 60dB. The function of the hair cells of this case seemed to be slightly deteriorated. DPOAEs could be recorded even in the cases in which EOAEs were not detected. In addition, the inner ear function in the high frequencies can be evaluated by DPOAEs.
Early language development in 14 young children under 3 years of age with profound hearing-impairments, who had been fitted with hearing aids and had received speech therapy at our clinic, was analyzed by the following five-points: starting age of training, intelligence quotient, upbringing environment, speech therapy program and hearing management. The main results were as follows: 1) In the children receiving speech therapy at an early stage (within eighteen months of age), 3 of 6 patients showed good development of early language but the other 3 had a rather delayed development. 2) All children having an inadequate environment of upbringing showed a markedly delay of learning to speak. Therefore, it was presumed that environmental conditions were most important factors in these children. 3) Concerning the training methods, the way in which the hearing-impaired children were taught together with their mother or another person was most effective, more than those with only other hearing-impaired children alone for early language development. 4) There were no children with deterioration of hearing loss, however 2 patients suffering from otitis media with effusion showed a slight delay of speech development. Most importantly, it was thought that speech therapy should be performed together with the periodic management of hearing acuity.
The relationships between pre-operative tinnitus nature and audiometric configuration, and also between tinnitus nature and pure-tone hearing level were investigated in 80 ears with surgically proven unilateral acoustic neuroma (AN). Subjective expression of tinnitus nature using onomatopoeias, and simulated tone and tinnitus frequency identified by pitch match test were analyzed. The results obtained were as follows; 1) When the incidence in use of each onomatopoeia was analyzed, the most frequently used onomatopoeia was “jie” (22.5%) followed by “zah” (12.5%). The incidence in use of “kien” was only 11.3%, which was the most frequently used onomatopoeia for the subjective expression in tinnitus ears without hearing loss or associated with cochlear deafness. 2) About 40% of simulated tones in pitch match test were found to be band noise or white noise. 3) When the tinnitus nature (onomatopoetic expression, simulated tone and tinnitus frequency) and audiometric configuration were compared, the close relationship was found between them. 4) When the tinnitus nature and pure-tone hearing level were compared, the close relationship was found between them. 5) Based upon these results, it was concluded that the relatively high incidence of noise tinnitus in affected ears of AN could be due to the different distributions of audiometric configuration and pure-tone hearing level compared with those in tinnitus ears associated with cochlear deafness.
To investigate the effect of steroid upon acoustic trauma, 32 albino guinea pigs were given 12 or 40mg/kg methylprednisolone (mPSL) i.v. and exposed to 2kHz pure tone of 110 or 120 dBSPL for 10min. The threshold of the compound action potential (CAP) were examined before and every 30min after the exposure to intense sound. The CAP threshold shift by acoustic overstimulation in these mPSL pretreated animals was not significantly different from that in the control animals. However, some mPSL given animals exhibited significant recovery in the CAP threshold during the observation period of 3 hours, while the threshold shift was quite minimal in the control. These results indicate that mPSL dose not exert in a protective manner but has presumably some effects on the recovery from the damage induced by acoustic overstimulation.
Air-bone gaps were measured at two sites, the mastoid and forehead, for 60 young adults with normal hearing. The following findings were obtained. 1. For bone-conduction at forehead, the probability of the air-bone gaps within ±5dB was about 60% and within ±10dB about 85%. The probabilities for the mastoid were lower than the forehead by about 5dB. It was suggested that the critical air-bone gap for conductive disturbance would be expanded. 2. The general misunderstanding that air-bone gaps of the normals is 0dB even for the normal individuals, could not be supported.
We made the auditory screening system at the three-year-old health examinations in Aichi Prefecture for the purpose of screening children with bilateral mild and moderate haering loss. According to the system in Tokyo, we used a questionaire and auditory tests of a whispered voice test and a finger friction test, as the first screening method, tested by parents. This system has been performed since October, 1992. During the first year, the tests were performed in 47, 223 children, and 10 children with bilateral hearing loss were found. They all failed in a whispered voice test or could not understand the test. One of the 10 children was not detected by the questionaire. If only the questionaire had been used, her hearing loss could not be found. We confirmed that the auditory tests at home as well as a questionaire was necessary. Except one child with bilateral mild hearing loss, 9 children had delayed development of speech due to heaing loss. Studying the 10 children, we found that there were problems as the system was conducted at home, in a health center, or in hospitals. So, we must conduct the system correctly.
We followed 55 patients (56 ears) with idiopathic sudden sensorineural hearing loss for more than one year and examined their audiometrical changes once a year. There was no difference in audiometrical changes between affected ears and unaffected ears. The hearing change on longterm observation didn't correlate with both prognosis and audiogramic pattern about 1 month after the onset. We considered that the damage in the inner ear had fixed after an acute period, regardless of the etiology of idiopathic sudden sensorineural hearing loss.
Measurement of the characteristics of bone conduction hearing aids is usually made by using an artificial mastoid. Therefore in the characteristics of a bone conduction hearing aids, there are nothing stated about the sound which can be perceived only through the bone conduction of mechanical vibrations. As a new appraisement, an equivalent sound pressure level related to vibrations on the mastoid was formulated and the process of getting an equivalent sound pressure level was described. Equivalent sound pressure levels for 1g accerelation applied to a forehead were also measured instead of measuring threshold levels.
A comparative study on the results with finger friction test and pure tone audiometry was undertaken on 77 patients (120 ears) at the ages of 3 to 32 years. The results obtained were as follows. 1) If successive rubbing noise produced by a dry index finger and a thumb could not be heard in 50-60cm apart, about 30dB hearing loss at 1000-2000Hz or above without masking could be detected by the examiners. Therefore, it was considered that the finger friction test was available for detecting presbycusis. 2) The examiner should confirm that his finger rubbing noise have a property that it's sound pressure increase as the frequency become high, because the noises showed individual difference in frequency property.