Acoustic reflexes were measured in ears with type A (static compliance<1.5cc) and type Ad (static compliance≥1.5cc) tympanogram in three pressure conditions of the external auditory canal: (1) the peak pressure, the pressure corresponding to the peak on a tympanogram, (2) the positive pressure, the peak pressure +50 daPa, and (3) the negative pressure, the peak pressure -50 daPa. Although the proportion of positive reflex in the peak pressure condition was lower in the ears with type Ad tympanogram than those with type A tympanogram, the reflex was detected in the negative pressure condition in the majority of the false negative cases in type Ad group, resulting in no difference in the positive rate between the two groups. On the other hand, in type A group, the mean reflex threshold was lowest in peak pressure condition, while in type Ad group, it was lowest in negative pressure condition and highest in positive pressure condition. All these results were similarly observed both in ipsilateral and contralateral stimulation. It was suggested that when acoustic reflex is not detected in peak pressure condition in cases with type Ad tympanogram, another measurement in negative pressure condition should be added.
We analyzed speech discrimination of patients with sensorineural hearing loss by applying an index of information loss (IL) which is showing conditional entropy in information theory. The consonants was compared with the voiced and voiceless consonants. In the present study, the patients was divided into 3 groups in age, 3 groups in augiogram type and 4 groups in hearing threshold level. The IL of the consonants was about 1 to 2 bits and the vowels was about 0.5 to 1 bits. The IL of the voiced consonants were about 1.5 bits and the voiceless consonants were about 2 bits. The results of nature with the IL of the consonants and vowels in age, augiogram type and hearing threshold level groups were as follows. The IL of the over 65 years of age group was more prominent than the IL of 10-34 and 35-64 years groups. The IL of the flat hearingloss group was more prominent than the IL of abrupt and descending hearing-loss groups. But the IL of 4 groups in hearing threshold level had no spesific tendency.
Auditory function of children with malignant solid tumors who were receiving cisplatin was assessed. Twenty six children, 7 months to 13 years of age, comprised of neuroblastoma (14 patients), rhabdomyosarcoma (4 patients), hepatoblastoma (3 patients), dysgerminoma (2 patients), yolk sac tumor (1 patient), pancreatoblastoma (1 patient) or immature teratoma (1 patient). All received several courses of intravenous administration of cisplatin (90mg/m2), ranging in total dosage from 240 to 1945mg/m2 (mean 908mg/m2). Out of 21 children examined by pure tone audiometry, 16 had highfrequency hearing loss and 5 were normal. Hearing loss was related to cumulative drug dosage, reanal function and age. There were 3 children who were tested for one or more years after treatment was completed. None showed evidence of recovery or worsening of hearing.
Relationship between change of EOAE and frequency of high intense sound were investigated in 10 ears exposed to high intense sound. TEP and HPP were used as parameter. After exposure to 1kHz pure tone with high intense sound, TEP and HPP of the EOAE evoked with 1kHz tone burst were more markedly suppressed than those with 4kHz tone burst. Otherwise, after exposure to 3.3-4.8kHz band noise in which the central frequency were 4kHz, TEP and HPP of the EOAE evoked with 4kHz tone burst were much more suppressed than those with 1kHz tone burst. These results suggested that that the frequency of sound which suppressed EOAE related to the frequency of the stimulus for the EOAE.
Kendo is a traditional Japanese Sport and it is controversy whether Kendo causes hearing loss or not. The purpose of this report is to study the effects of a hitting sound and shock by “Shinai”, a bamboo sword, during Kendo exercise. The hitting sound level were measured under the next three conditions; Menhimo, a belt for fitting “Men-Mask” is fastened hard, fastened ordinally, and using an air cushion inside a Men-Mask. As a result, the hitting sound level was over 120dB when the Men-Mask was fastened hard. Shock was estimated by measuring the vibration acceleration level under the next five conditions, the Menhimo is fastened hard, fastened ordinally, using an air cushion inside the Men-Mask, feather or a styrol shock absorber. The vibration acceleration level was 77.7dB when the Menhimo was fastened hard. However, if the air cushion was used inside the Men-Mask, the hitting sound level was decreased by 10dB, and the vibration acceleration level was about 1/70. We speculated that the hitting sound level and shock by Shinai had an excessive effect on inner ear, therefore Kendo exercise for a long time might cause a hearing loss.
To investigate the therapeutic effect of steroids on acoustic trauma, albino guinea pigs were exposed to 2 kHz pure tone of 110, 115 or 120dB SPL for 10 minutes, and then given 12 or 40mg/kg methylprednisolone (mPSL) i.p. daily for the following week. The threshold of the compound action potential (CAP) was exmined at the 7th day and the results were compared with those in the control group given physiological saline instead of mPSL. The CAP threshold shift by acoustic overstimulation in case of exposure to 115 or 120dB SPL sound was not significantly different from that in the control animals. In case of exposure to 110dB SPL, however, the CAP threshold shift in the mPSL given animals was significantly smaller than that in the control. These results indicated that mPSL is effective in case of mild acoustic overstimulation.
Results of speech discrimination tests in 38 patients with sensorineural hearing loss were analyzed from the view points of communication ability and cues of Japanese consonants. The audiograms of all the patients showed abrupt-type highfrequency hearing loss. The results and conclusions were as follows. 1) Recognition of Japanese consonants was highly disabled in the patients whose hearing thresholds at 1000Hz were high. 2) Cues of the voiceless consonants without /s/ distributed in the frequency range below 1000Hz. 3) Cues of the voiced obstruents and nasal consonants distributed in the frequency range above 1000Hz.
Although amplitude of the tympanic membrane vibrations is very few in nanometer when we make conversations, we can understand clearly what the other one says. This is speculated to be caused by the cochlear amplification. Otoacoustic emissions (OAEs) are recognized as the byproduct of this cochlear amplification, however, the mechanism of amplification in the cochlea is obscure. Therefore, in the present study, a laser Dopplar vibrometer coupled to a compound microscope was used for the measurement system. Then, an attempt was made to measure directly the basilar membrane vibrations of the cochlea of guinea pigs in live, ded and hypoxic conditions, and also when distortionproduct OAEs (DPOAEs) were generated. The results were as follows: the amplification of the basilar membrane vibration, which represented the cochlear amplifier in the live guinea pigs, was influenced by the moderate hypoxic, and contributed to the generation of DPOAEs.