By use of a measuring apparatus of speech articulation utilizing in our department, the mishearing phenomenon of thirty mono-syllables in Auditorially Balanced (AB-) List of Japanese language proposed by Prof. Kawata was observed simultaneously with the frequency analysis by a visible frequency analysator (TS-6 type), the recording of this procedure being made by 8 mm cinematography.
Furthermore, the interrelation between the mishearing and the frequency analysis of monosyllables was investigated by successive tracing of the temporal change of speech spectrum.
(1) Even in normal ears, the mishearing can occur in the particular speech sounds on the same vowel elemtal line. From a fact that, frequency-analytically, the speech sounds on the same vowel elemental line, of which back vowels are common, has the similar intensity distribution of a chief frequency area and the tone which gives the property characterizing the speech is the front consonant, it is observed that the mishearing results chiefly from the similarity of distortion of a front consonant in amplitude, frequency or duration.
(2) In the examination of deafness, the pure tone hearing curve was classified into eight types and the pure tone hearing loss was observed in five stages such as 0-20, 21-40, 41-60, 61-80 and above 81 db. And the speech hearing curve was described by the classification of Tateishi.
(3) The mishearing in deafness, as in normal ears, frequently occurs in the particular speech sounds on the same vowel elemental. line, especially occurs in the speech sounds containing a Formant distorted in frequency, observing from the pure tone hearing curve. The hearing loss has no direct relationship with the mishearing; namely when the intensity of tone is increased there occurs no change in mishearing. The tendency of mis-hearing is common in various kinds of deafness.
(4) In both intact and deaf ears, the mishearing occurs most frequently in Mi, Me, Nu, Bu, Be, Pe, in which “Mi” and “Me” or “Ma” column and “Na” column have frequency-analytically very similar Formant and shows a very slight difference due to the time shift of development of frequency area. From these facts, the increase in the ratio of mis-hearing can be explained. Since the voiced consonants tend to become noise because of the vibration of vocal cords by phonation the mis-hearing of a sonant is frequently observed in “Ra” column, being a voiced consonant. This fact is presumably due to the semi-vowel character of speech sounds on “Ra” column.(author's abstract)

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The audiograms in 102 cases of head trauma have been classified in 8 types (Kawata), with use of the NY-A audiometer and Onchi's ear-plung-method of bone conduction on the other hand the lack of vitamin B₁ has been examined by colouric reaction of urinary pyruvic acid (by Sawada).
C (abrupt) type was most frequently observed, then B (horizontal) A (normal), and D (descendent) type, the last being dip type. Amang them the hard of hearing in 84. 8 %, the perceptive deafness observed in half of them.
In the cases of head trauma at the temporal region the mixed or the conductive deafness was more often, while in the cases of trauma at the face or the nasal radix, the perceptive deafness was predominant. The severe trauma resulted in the mixed, or frequently resulted in the perceptive deafness of C type or dip type.
The C⁵dip was often caused by a slight trauma at the face or at the nasal radix. The head trauma, in spite of its localization causes the bilateral impairment of hearing: for example, four cases of Contre Coup, out of 64 cases of which trauma was got unilaterally, were observed.
From a fact that B₁-avitaminosia can be observed in 68. 1 % of cranial trauma, the lack of vitamin B₁ may be an important factor for producing the hearing impairment due to commotio labyrinthi.

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By use of conditioned dogs for objective hearing test to which a blunt head injury through an apparatus, manufactured by author being able to give an impact in various intensities arbiturally, the hearing impairment of animals and the recovery of it were continuously investigated. The results in the present experiments should be supposed to be due to commotio labyrinthi from the blunt head injury.
After the one blow of 120kg cm, the impairment of hearing at 4096 cps was most remarkable with the simultaneous use of nor-adrenaline, but it was also some what observed without use of nor-adrenaline: this auditory affection in the case which treated previously by Depot-Kallikrein, however, being slight. In each group of animal experiment series the recovery was very rapid, except the very slight hearing losses in higher frequencies after 24 hours.
After the three blows of 120kg crn daily for five days, there was a significant difference between the case with or without treatment of Depot-Kallikrein, and the impairment of hearing at 4096 cps was remarkable in the nor-treated group.
The recovery of this group was very slow. And it required six weeks for the recovery of 4096 cps in the non-treated group, while it needed of two weeks in the Depot-Kallikrein group.
The C⁵dip, appeared most frequently in the nor-adrenaline group, is probably caused by local ischemia in the cochlear basal turn. Commotio labyrinthi tends to affect upon the intralabyrinthine circulation in vulnerable cochlear basal turn. Therefore the most severe impairment was recognized at 4096 cps.

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The author has clinically observed on the various groups of DIISM-user such as the first group (37 persons without any subjective hard of hearing), the second group (11 persons who have been audiometrically examined even before application), and the third group (40 persons that DHSM and 20 mg of Vitamin B₁ were simultaneously applied.)
1) Six of 37 persons of the first group showed the unconscious hearing impairment at the high frequency area.
2) In the observation of the change of hearing sensation before, during and after application in eleven persons of the second group, three showed the permanent loss of hearing.
3) In 48 persons of the first and the second group without any subjective hearing loss, 9 (18%) showed the impairment of hearing, in which 7 revealed hearing loss by use of the total dosis below 30 g of DHSM, and in 7 cases among nine cases revealed the hearing loss at the high frequency area bilaterall and in 2 cases unilaterall.
4) In the serial observation of audiometric results before, during and after the simultaneous application of DHSM and 20 mg of Vitamin B₁ to 40 persons of the third group, the loss of hearing was not observed during the application, and only a case of unconscious slight hearing impairment was audiometrically seen after two months, however, in other cases any hearing complaints being not recognized.
5) From the audiometrical results, it is supposed that the simultaneous use of DI-ISM and 20 mg cf Vitamin B₁ can prevent the occurrence of DHSM-deafness.

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