Author designed a new procedure to assess intensity difference limen (I. D. L.) in normal person and in patient with hearing loss, -utilizing the apparatus for the SISI of a commercialized audiometer and adopting psychophysically the up-and-down method. I. D. L. to low tones (250Hz and 1000Hz) in normal ears could be expressed by one hyperbolic function of sensation level, from 5dB to 80dB re S.L. At 4000Hz, also at 8000Hz, two hyperbolic functions were needed for each range above and below about 40dB re S.L. I. D. L.'s in patients with sensori-neural deafness, being measured by the same procedure and compared by the sound pressure level of the sustained standard tone, were equal to the normal I. D. L.'s above a certain level, just as the loudness of impaired ear becomes equal to that of normal ear in Fowler's method. This intensity level, above which I. D. L.'s of deaf ears proved to be normal, was named as the recruiting level. The intensity range between the recruiting level and the elevated threshold level, which was named as the recruiting range, was supposed to be essential for the deaf ear to percept the intensity change. It was deduced that even in normal ear a critical intensity range, something like the recruiting range of pathological ears, should be present. I. D. L.'s in ears with conduction-loss could not be compared with that of the normal ear in the above-mentioned manner, because the sound energy, before arriving at the sensory part, was converted in various ways by the pathological conditions.
Statistical observations of the 5049 persons with severe hearing loss of over 60dB in conversational area from 1951 to 1968 in Tochigi Prefecture were made. They were classified as follows; deafness including deafmúte: 1849 cases (37%), perceptive deafness: 1626 cases (32%), mixed-type deafness: 1392 (28%), and others: 172 cases (3.4%). 90% of perceptive deafness had unknown etiology, while more than 82% of mixed-type deafness were related to chronic otitis media. The occurrence of congenital deafness has not been changed during the past 40 years. In the cases of congenital deafness, the consanguineous marriage was found higher than in those of the acquired deafness. These tendency was also suggested in the regional distribution of the occurrence of the deaf. In the former the familial occurrence of deafness and/or severe hearing loss was also higher than in the latter. Severe hearing loss due to chronic otitis media has been decreased rapidly with the development of antibiotics. Both perceptive and mixed-type deafness tended to increase in number with the age. Further investigations on symptoms, onset and progress of deafness, the effect of hearing aid and the presence of tinnitus and vertigo were made in the above-mentioned deafness. It was suggested by the detailed history taking that it is possible to detect more cases of streptomycin deafness out of the cases of perceptive deafness with unknown etiology.
The oxygen consumption of the membranous cochlea, brain, liver, kidney and muscle of shaker-1 mouse and normal mouse (CBA J strain) was measured with the use of the Warburg respirometer. The mean value of the oxygen consumption of the membranous cochlea of shaker-1 mouse was less than that of normal mouse. As for the values of the oxygen consumption of other tissues, there was no significance difference between the two strains.
Clinical examination for head noises was conducted in 1701 cases of head trauma, and the findings were studied in relation to tinnitus produced by the same cause. The result of this study is as follows: 1) Head noises were defined as a case in which the sound sensation is felt to be located intracranially, but not in the auditory system. These cases fox our study were chosen by questioning. 2) Head noises were found in 138 of these cases. Those of pure head noises numbered 31, which corresponded to 2.13% of the entire cases, and so were very rare. Most of these cases of head noises were combined with tinnitus, numbering 107. 3) In the rate of continuous type to intermittent type there was not much difference between head noises and tinnitus. 4) The cases of disappearance of head noises were very rare, being only 2.13% and those of tinnitus were 12.85%. 5) The most frequent sound of both head noises and tinnitus was sound-Ji, and this sound was more frequently found in tinnitus. 5) Rhythmic sound was found in more cases of head noises than in the cases of tinnitus. About two thirds of the whole cases of head noises bore a resembrance to those of tinnitus in their nature of sound. 7) The percentage of the frequcency matched to head noises or tinnitus existing in the high frequency range was found greater in the cases of head noises than in those of tinnitus. 8) As one of the causes of head noises, intracranial circulatory disturbance was presumed.
Electrophysiological experiments were performed in order to evaluate an effect of thiamine derivative on the kanamycin ototoxicity. Cochlecr microphonics of the rabbit was measured day-to-day with the electrode permanently implanted on the round window. One group of animals were daily given i.p. injections of kanamycin of 100mg/kg (group I). The other group got the same dose of kanamycin plus thiamine derivative (O, S-dicarbethoxythiamine) of 20mg/kg (group II). 1) The curves of CM amplitude showed that there was a wide difference in the periods of onset of reduction. The curves of group II showed a more wide difference than that of group I and in a few animals of group II the periods of onset of CM reduction were far prolonged beyond that of group I. 2) The clear-cut difference was observed in the slope of CM reduction between group I and group II. i.e. in the group I CM was reduced rapidly, while in the group II it was reduced with a gentle slope until the CM came to low valtage.
The present study was designed to clarify the way in which sensory motor self control function in vowel articulation in children developed, by the investigation in to the way of development of the amount of information transmitted in vowels of different age children. The result was the fact that 7-9 year old children showed the same amount of information transmitted as that of adult.
As a study on sensory-motor self control function in voice and speech behavior, the measurement of voice and speech motor function under the condition of auditory masking and normal were performed, in order to clarify the function of auditory feedback control. The result was that there was a statistical significant difference of motor variability between both auditory condition at 0.05 level.
The binaural fusion phenomenon was discussed in relation with the formation of sound image, binaural masking, binaural hearing test using synthetic vowels and binaural speech hearing test. It became evident that sound image was able to recognize by using two filtered pulses binaurally and the sharpness of sound image effected according to both frequency and intensity of these two pulses. The recruitment phenomenon or hobble phenomenon was observed according to the frequency ranges of two filtered pulses on the binaural masking phenomenon (provisional name). The real summation of binaural hearing was noted particularly in the area of /e/, when F1 and F2 components of synthetic vowels were used separately in each ear. The inhibition phenomenon through the other ear was recognized more frequently by using time distorted speech than frequency distorted speech. To summarize our interpretation of the results, we can estimate that there is a large difference in the central nervous mechanisms of binaural fusion phenomenon between time distorted speech and frequency distorted speech.
The impedance of the human tympanic membrane has conventionally been measured by the indirect methods developed by such researchers as Tröger, Schuster, Møller, Zwislocki, and Morton. As the result of the studies of these methods, Onchi proved that a modified Tröger's method is adequate in its clinical application, and deviced new equipment. Fig. 1 shows a block diagram of this equipment. A small earphone of high acoustic impedance is driven by an oscillator and sends sound waves to an acoustical tube, which is variable in length. At the opposite end of this tube, a perfect connection is made by an ear-piece to the external auditory canal of the test ear. A probe tube microphone is inserted into the acoustical tube immediately at the front of the earphone. Standing waves are brought about in the acoustical tube by changing its length, and then sound pressure at the tympanic membrane is measured by the microphone under two special conditions of resonance and antiresonance. The impedance measured by this device is calculated and divided into two components, such as resistance R and reactance j (Mω-S/ω). Where M is mass, S is stiffness, j √-1, and ω is angular frequency. The measured impedance of the tympanic membrane is represented by the equations described in this paper. These equations require that four values be measured by this device as follows: 1) The length of the acoustical tube dT is measured by the scale (in mm) when the maximum sound pressure is produced in the tube connected to the auditory canal of the test ear. 2) The length of the acoustical tube d0 is measured by the scale when the maximum sound pressure is produced under a special condition when the tube is closed with a rigid wall at its end; i.e., under a condition where the tympanic membrane is replaced by an infinite high impedance. It is necessary in this measurement to make a volume equivalent tube. This tube can be made variable in length by a sliding rod and made equal in volume to the air cavity of the test ear. Thus the length d required by the equations is obtained by the difference of dT-d0. 3) rT is a ratio of the maximum sound pressure to the minimum in the acoustical tube when connected to the auditory canal. 4) r0 is a ratio of the maximum sound pressure to the minimum when connected to the volume equivalent tube. It was found by our experience that reactance is available for diagnosis of conductive deafness with nonperforated tympanic membrane. The measured reactance in cases of normal condition and otosclerosis, as well as in cases of ossicular chain separation is as shown in Fig. 5. Otosclerosis is higher in reactance, compared with the normal ear, about-j1500 acoustic ohms at 500Hz. On the contrary, the ear with ossicular chain separation is lower in reactance, such as-j300 acoustic ohms at 500Hz. The shadowed area in figures indicates the range of reactance of normal tympanic membrane. The resonance-frequency of the tympanic membrane is found by checking a frequency at which reactance becomes zero. The frequency of resonance is shifted to lower frequency in cases with ossicular chain separation, such as about 700Hz, while normal and otosclerotic ears in a range of 1200Hz to 1500Hz. The ear with ossicular separation shows a particular trend of reactance which is always in the direction of +j in a frequency range of 700Hz to 1500Hz. The impedances were measured in otosclerosis before and after stapes mobilization operation. After the surgery, the reactance changed to normal value in successful cases (Fig. 6). The impedance after fascia-flap-used tympanoplasty were also measured (Fig. 8, 9, 10). Along the post operative course, the increase of stiffness and decrease of mass of the tympanoplastic membrane were generally observed. These findings run parallel with increase in better conductivity of the membrane.
Audiometric examination was performed on 120 subjects who engaged in speaker research or in administrative works in speaker production, 10 subjects who used in their work insert-type receivers, and 30 recording engineers. The results were analized in reference to the number of years in works. Present study revealed that: 1) there was no tendency that hearing was impaired in speaker engineers or in other people exposed to sound from speakers. 2) the mechanism of hearing loss at 4000Hz found in recording engineers was appeared either different from the ones seen among sheet-metal workers or in speaker engineers. 3) the reproduced sound through speakers seemed not to cause hearing loss in human. 4) the direct sound produced by instruments may cause hearing loss as in the case with noise, however, further observation is to be done to prove definite effect of the sound from the instruments.
On the previous report, in cooperation with the members of the Tokyo Diabetic Society, we indicated that the perceptive deafness including the insensible deafness of diabetics amounted to 48 cases of 127 cases. And the result was excepted from non-diabetic factor. This report is the results of follow-up retest through one year on 32 cases of 48 cases previously confirmed. 1) 11 cases (37.5%) are in advanced stage of perceptive deafness, 13 cases (40.7%) are in constant, 4 cases (10.9%) are in convalescent stage, and 4 cases (10.9%) are in unstable condition. 2) It is found that many cases in short term suffering are in unstable levels of hearing-loss. 3) All of the cases in convalescent stage of perceptive deafness are found in good blood-sugar control group, advanced or unstable cases are found in poor blood-sugar control group, and many cases of constant stage are found in good control group. 4) We noticed the diabetic retinopathia or other ophthalmologic disorders in advanced stage of many cases of perceptive deafness. 5) But we discovered no mutual relation with the change of perceptive deafness and other results of clinical test.