Distortion product otoacoustic emissions (DP-OAE) (2×f1-f2) were measured in guinea pigs with approximatemly 4kHz primary tones (f1=3.9875kHz, f2/f2=1.225). DP-OAE was measured in all normal subjects. They completely disappeared after asphyxia for two minutes. The effects of intravenous injection of lidocaine on DP-OAE were examined. DP-OAE was increased after lidocaine injection for about 15 minutes, and returned to the normal state. This increase suggested direct or indirect effect of lidocaine to the cochlea, and possible relation of cochlear efferent pathways.
It was recently revealed that in hearing loss of cochlear origin, the distortion-product otoacoustic emission (DPOAE) level plot against primary frequency reflects hearing threshold pattern very well. One would naturally expect that the test might provide objective data to estimate hearing thresholds. This possibility was tested by analyzing correlation between the pure tone audiometry thresholds and the DPOAE levels at 2f1-f2, in various degrees of patients with sensorineural hearing loss. Very good linear correlation was found between the pure tone thresholds and averaged DPOAE levels in the patients with mild to medium sensorineural hearing loss (<50dB). The correlation coefficient was especially high when the f2 frequency was adjusted to the test frequency of the pure tone audiometry. However, the DPOAE level variances were so large that it was difficult to predict hearing thresholds of patients from DPOAE levels measured in their ears. These rusults indicated that the DPOAE level measurement certainly leads to objective quantification of some aspects of cochlear function, but it is dangerous to estimate the hearing threshold values solely from this test.
Two patients with hearing loss due to mumps showed unusual clinical features. Both patients showed no parotid swelling, but serum examinations revealed mumps virus infection. The first case; a 3-year-old girl developed fever and neurological signs. MRI findings were compatible with mumps encephalitis. The second case: 47-year-old woman complained of tinnitus and hearing loss initially. The hearing impairment was moderate in 2 months after the onset of desease, but became profound deafness later. Anti-mumps IgM antibody was demonstrated by a serum study of ELISA method in those patients. Usefulness of ELISA methhod to examina IgM antibody was discussed.
In the instantaneous time-varying spectral analysis of auditory middle latency response (MLR) and auditory slow vertex response (SVR), The time-varying spectral analysis represents both the time and frequency characteristics of MLR and SVR at the same time. The results of the time-varying spectrum (TVS) were as follows; The dominant frequency range of TVS of normal MLR was concentrated at around 40-60Hz. The TVS showed its peaks at around the latencies of each component of MLR. The TVS of normal SVR had the prominent magnitudes in the frequency range of 3-7Hz, and had its peaks at around the latencies of each component of SVR. There was a marked tendency observed under 10Hz in the frequency range; the relative magnitude in the lower frequency band was increased, according to the longer latency components, from N1 to P2.
Four hundred sixty-three children aged 5 to 15 years old, visited the Department of Otolaryngology, Iwate Medical University during the past three years, were examined by conventional audiometry. Presence of subjective tinnitus was clearly recorded, and the patients were clinically studied The results were as follows; 1) Of 463 children, 30 patients presented with continuous tinnitus (6.5%) and 160 with intermittent tinnitus (34.5%). 2) The incidence of tinnitus increased with age, in both continuous and intermittent tinnitus. 3) Tinnitus was observed more frequently in the patients with hearing impairment, and continuous tinnitus was observed in those with perceptive hearing impairment, and intermittent tinnitus was observed in those with conductive hearing impairment. 4) Mean hearing level in the patients with continuous tinnitus showed to be 8.9dB higher than that with intermittent tinnitus. 5) Onomatopoetic expression of tinnitus in 18 cases were relatively few in its quality.
The psychosomatic symptoms complained by brothers and sisters of hearing-impaired children were studied by sending questionnaire. The symptoms of neurotic manifestations such as abdominal pain, facialtic, leg pain, stuttering, over eating and stealing were seen in 17 of 47 cases. These symptoms were observed in the patients who are living not together with their grandfather and grandmother rather than the patients living together with grandparents. These symptoms were improved by a contact with familiar communications between parents and children within one year in most of cases, however, persisted over one year in other cases. Therefore, it was presumed that these symptoms would be caused by frustration of affection of children. In conclusion, in treatment of hearing-impaired children, it was thought that brothers and sisters of hearing-impaired children should be consulted.
Auditory brainstem responses (ABR), middle latency responses (MLR) and slow vertex responses (SVR) were recorded in patients with central lesion. The responses were assessed using logarithmic time scales. The recording to acoustic stimuli was carried out on the vertex-ipsilateral mastoid. The stimuli sound was click and the averaging numbers were 500 times and analysis time was 500msec. Pass-band of the filter was 2-200H. The results were as follow; 1) Two patients with acoustic tumors showed aprolongation of I-V interpeak latency (IPL) on ABR. 2) Another patient with acoustic tumor showed nowave II to VI on ABR and decreased amplitude of each component of MLR and SVR. 3) Another patient with acoustic tumor and pons bleeding showed no ABR and MLR. 4) A patient with bleeding of the pons showed aprolongation of III-V IPL on ABR. 5) A Patient with midbrain bleeding showed a prolongation of I-V IPL on ABR and absence of Pa-Na-Pb component of MLR. 6) The patients of cortical lesions showed various kinds of abnormality of MLR. 7) All of the patients showed a normal P2 of SVR.
The relationship between functional insertion gain and articulation scores for consonants was studied in patients whose hearing aids have been satisfactorily used for their normal daily activities. Since most of the patients examined in this study were elderly, we performed two 20-item monosyllabic discrimination tests instead of a 50-item monosyllabic discrimination test. The rate of improvement in the articulation scores for consonants was determined by combining the results of the two tests. The results indicated that the functional insertion gain at 1500Hz tended to be correlated with the rate of improvement in articulation scores for voiced consonants, while the functional insertion gain at 3000Hz and 4000Hz tended to be correlated with the rate of improvement in articulation scores for voiceless consonants. Individual differences in the reception of voiced consonants were considered to be greater than for voiceless consonants.