The auditory response in which the eyes were opened slowly when the sound stimuli were presented to the subjects soon after their eyes were closed when they are going to fall into sleep was called as the auditory eye opening responses at falling into asleep (AER). Fifty-five infants with normal hearing, ranging from five days to two years of age, were tested by AER. Sixteen autistic, mental retarded, and hearing impaired infants, aged one to three years, were examined in this study. The results obtained were as-follows: 1) In autistic and mental retarded infants, who did not respond to conventional audiometric techniques, AER were observed in all. 2) Infants with moderate hearing impairment did not show AER. 3) AER was evoked by warble tone (1kHz, 3kHz 50dB (A)) or click sound produced by the tongue (50-60dB (A)) in more than 90% of the subjects with normal hearing. 4) Most of the newborn infants failed to receive the test, because they were always closing their eyes. 5) AER was characteristically evoked by weak sound stimuli and the occurance of the response was very frequent. 6) AER was thought to be useful for children who hardly respond to the conventional audiometry. 7) In conclusion, it was suggested that AER is useful as one of the audiometric batteries or as a screening test for infants if performed properly in proper time.
Auditory brain stem responses (ABR) on acoustic stimulation using clicks were recorded in 13 preoperative acoustic tumor cases and 10 postoperative cases. The response pattern of each wave, latencies of wave V, I-V interval, interaural latency difference (ILD) in wave V and I-V interval difference (ID) were compared with those of normal hearing persons and with the responses in cochlear hearing loss. The results were as follows: 1) Wave V was obtained in 45% of the preoperative cases examined. In 27% only wave I was observed and in 27% no responses were recognized, in all of which the tumor size was large. In postoperative cases wave V was seen in 30% and wave I only in 20% and no responses in 50%. 2) Findings were considered to be abnormal when ABR showed the followings: i) Wave V latencies were longer than 6.9msec. ii) I-V interval was longer than 5msec. iii) ILD was greater than 0.4msec when the average of the hearing loss at 4KHz and at 8KHz was within 40dB and if higher than 40dB, the ILD was greater than 0.85msec. iv) ID was greater than 0.4msec when the difference in the above average hearing loss between the right and left ears was within 40dB, and if higher; then ID was greater than 0.53msec. 3) According to these criteria, ILD and ID were positive in all tumor cases except those of bilateral acoustic tumors. 4) The response pattern (wave configuration) was not related to the hearing loss or audiogram pattern. 5) There were no consistent relations between the tumor size and ILD, or ID in acoustic tumors of moderate size. It seems difficult to estimate the tumor size from ILD and ID and other ABR findings. Even in the cases of small tumor confined in the internal auditory canal, only wave I was observed. 6) Incidence of positive ILD and ID for the diagnosis of acoustic tumors are higher than those of the positive stapedius reflex tests. Therefore, ABR is considered to be the most effective objective test available today.
The generator of acoustically evoked middle latency response (MLR) and the posibility of reversible changes of MLR induced by transcient and local blood flow deficiency were investigated in cats. The results were as follows: 1) The generator of Na-component of MLR was located at the contralateral medial geniculate body to the sound stimulus, however, Pacomponent was suggested to be generated from the widespread central area. 2) The reversible changes of Na-component were induced by transcient and local blood flow deficiency by ballooning a part adjacent to the medial geniculate body.
This paper is to investigate the possibility of obtaining of the stable auditory slow vertex response by applying white noise to the unexamined ear during test. The intensity of the noise is approximately 40dB above the threshold. The results were as follows: 1) SVR in sleep showed the definite tendency to be more stable when white noise was applied to the unexamined ear than without white noise. 2) In awake state, the effect of white noise was not evaluated, and this is simply due to a fact that SVR can he observed clearly in awake condition: 3) During the procedure, variation of the power spectrum of back ground EEG in α frequency range was less with white noise than those without white noise.