In order to examine children's auditory discrimination ability of speech sounds, the results of two popular methods were compared. The subjects were 59 of 4-year-old and 33 of 5 year-old children whose articulation of /t/, /k/, and /t∫/ sounds were normal, and their ability to discriminate these sounds was supposed to be normal. All speech sound used as stimuli were eight Japanese syllables: [ta] meaning “rice field”, [te] “hand”, [to] “door”, [ka] “mosquito”, [ki] “tree”, [ke] “hair”, [ko] “hen's cry” and [t∫i] “blood”. Each subject was asked to point a pair of pictures showing [ta]-[ka], [te]-[ke], [to]-[ko], [t∫i]-[ki] after the stimulus sounds were delivered (choosing picture test), and also each was asked to answer “same” or “different” to the stimulus sounds given in a pair (same-or-different test). Correct responses more than 75% were obtained in 91.5% of subjects in choosing picture test and 74.6% in the same-or-different test in 4-year-old subjects, and 100.0% in choosing picture test and 94.0% in the same-or-different test in 5-year-old subjects respectively. Difference of each result was statistically analysed. The conclusions were as follows: 1. Both methods were not satisfactory for a few subjects who could not follow the test procedure. 2. For 4-year-old children, choosing picture test was more adequate than the other.
A new play audiometry was devised, in which a popular TV program for children was used as reinforcement by Video Tape Recorder. APPARATUS: Infant Audiometer (Rion, MA-68) was connected to Video Cassette Recorder (Sony, VO-1720) and TV setting (Sony, PVM-2020). SUBJECTS: Thirty-one normal children aged 2 to 4 years were tested. TEST PROCEDURE: Principle method was the same as that of Peep-Show test by Dix and Hallpike (1947). The warble tones (frequency deviation: 10%) of 500Hz, 1, 000Hz were given to the subjects as stimulus sounds by descending method. RESULTS: Percentages of children whose audiograms were obtained were as follows: 70% in 2-year-old children, 93% in 3 and 100% in 4. Each average threshold was 7.9dB (JIS-1956) for 500Hz, 4.4dB for 1.000Hz, 10.0dB for 2, 000Hz in 2-year-old subjects, 4.6dB, 3.9dB and 8.2dB in 3-year-old subjects, and 5.8dB, 2.5dB and 3.3dB in 4-year-old subjects respectively. CONCLUSION: We concluded that our VTR audiometry would be usable as a clinical hearing test. It was left for further study on this VTR play audiometry to use TV spots as stimuli and rewards for response, and to apply this audiometry to normal and so-called difficult-to-test children.
Impedance audiometry was performed in patients suffering from sensorineural hearing loss using an Otoaddmittance Meter of the Grason-Stadler Model 1720-B. A type tympanogram with the 220-Hz probe tone, usually observed in normal persons, was found in 71 ears of one hundred ears examined. In other 29 ears, were obtained type B, C, D or E type tympanograms were obtained. When a 660-Hz probe tone was employed, other types of the tympanograms than type A were obtained in 53 ears of tested 100 ears. In 17 cases of 71 type A tympanograms with the 220-Hz probe tone, tympanograms with a 660Hz probe tone were of either type D or E. When both ears in one subject were examined, the same type of tympanograms on both sides was observed in 56 ears in 64 subjects. The otoadmittance values calculated in the 25 ears at the 220-Hz tympanogram and in the 27 ears at the 660-Hz tympanogram were larger than 5% critical limit value obtained for the normal subjects. By these findings, the possible participation of the middle ear disease in etiology of the sensorineural hearing loss was discussed.
Investigation was carried out on the problems that involved with school children who have hard of hearing, and that from what degree of hearing loss hearing aids become necessary to the children. The following points were particulary investigated. 1) The relation of the hearing impairment of the children to school attendance. 2) The aided threshold that the hearing-impaired children made the volume control setting of hearing aid by themselves. As the results, we believe that if the threshold at 1, 000Hz is below 40dB, the hearing aid is not absolutely necessary. On the contrary, if the threshold is over 50dB, the hearing aid is definitely necessary.
BSR audiometry was administered to 20 normal and 44 hearing impaired subjects. The hearing impaired group consisted of 15 subjects with flat loss, 17 high tone loss and 12 low tone loss. One-and-a-half cycles of a 500Hz sinusoidal wave (500Hz click) and one cycle of a 3kHz sinusoidal wave (3kHz click) were used as stimuli. Intensities of these stimuli were calibrated by the averaged subjective threshold from 20 normal hearing ears. (dBHL) In normal subjects, the averaged threshold of the BSR evoked by a 500Hz click was 13.1dBHL and by a 3kHz click, 4.2dBHL. BSR frequency specificity was determined by measuring the BSR (to 500Hz and 3kHz clicks) in hearing impaired subjects. The 500Hz click evoked a BSR in subjects whose pure tone audiograms were impaired above 500Hz. Also, in cases of low tone hearing loss, the BSR was evoked at the best-hearing frequency above 500Hz. The 3kHz click evoked a BSR in subjects with hearing impairment above 1kHz. These results indicate that the BSR provide information regarding hearing ability as low frequency as 500Hz.
The condition which mostly affects the threshold value in the pure tone test is background noise. For that reason, comparison of the test results from various testing institutes is not reasonable. It is obvious, however, that there are differences which are not negligible among the test results even from examination rooms with less than 50dB A, which satisfy the condition advised by ISO for a quiet room. Therefore, we used several audiometers (ISO) of the same quality and they are calibrated at the same intervals, and we selected several experienced and inexperienced persons as examiner and examinee. The factors such as the pressure of the earphone, rotation speed of the attenuator and seriousness of the examiner and examinee were analysed to elucidate the cause of the errors appeared on audiograms. As the result, there was always an error of 2.88dB depending on the audiometerc equipments including the receiver, even though the strictly corrected audiometer was used. The other factors, while the individual one was small, contributed to increase the error approx. to 8.52dB when they were added, and even though the background noise was of the same level and tone, approx. 10dB difference, depending on the testing institute, could be existed.
A method of input, output and analysis of hearing result by using the computer system was reported. Several results including the audiogram display in a form similar to ordinary manual audiometry were illustrated.