Those who work in factories or in high-speed transport facilities are generally exposed to vibration all over the body as well as to noise. On the influence of noise and vibration that the acoustic organs are subject to, a lot of tests on animals have been made, but none on human beings.
Using a new vibration-generator of my own devising, I tried a test on ten healthy young men and women. The conditions under which I tried the test were as follows: the frequency of the vib., 1000 per minute ; the amplitude, 3 mm ; pitching vib. ; the period of the test, 30 minutes at a time. The result of the test has revealed the fact that vibration adds to the power of hearing, white noise (white noise, 100 phon, 30 minutes) considerably attenuates it. But when vibration and noise are given at the same time, it gets still weakened. The hearing loss is striking at and around 4000 cps and C⁵ dip gets still more deepened than when it is caused by noise alone. The hearing loss in high and lowcompass is not evident.
Next I measured the retraction grade of the eardrum, by means of giving pure tone (1000 cps, 100 phon) to the ear immediately after charging them with vibration. When the vibration was given, the eardrum caved in actively and its angle was great, which, however, were weakened with the charge of noise.
From the above-said results, I have got to the conclusion that the existence of vibration is not harmful to the acoustic organs in itself, but when attended with strong noise, it becomes very harmful.

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The author performed an objective audiometry, forming a conditioned reflex of pupilla to light stimulation in rabbit as fundamental experiment before making an experiment on the DHSM-deafness. The result was acquired as follows: miosis as positive conditioned reflex was rather difficult to get, while mydriasis as negative conditioned reflex to white noise was easily perceived and lasted for a quite long time.
Having reference to the fact that conditioned reflex can be formed sooner when the pure tone of conditioned reflex is so faint as auditory threshold, it is conceivable that the inhibition appeared in this experiment has relation to the mydriasis provoking as non-conditioned reflex which has been recognized as acoustic pupillary reflex by intense sound stimulation. From these facts, the author concluded that it is unsuitable to apply an objective audiometry of rabbit for experimental studies of the long duration.
By use of an objective audiometry of conditioned animals, the author observed the hearing impairment caused by the use of dihydrostreptomycin. The author classified the conditioned dogs into several groups and observed the change of hearing acuity: the group for which DHSM was applied and the group for which vitamin B₁ in combination with dihydrostreptomycin.
1) DHSM was used 50mg/kg a day and 200mg/kg a day for the first group and third group, respectively. Comparing with the first group, 4 times dosage was applied for the 3rd group; but it did not cause severe hearing impairment in early stage. Approximately 10g for the first group and 20g for the 3rd group, in other words, about 10-20g total usage caused the hearing impairment. There was a range in the total use of the medicament to bring out the appearance of hearing impairment. Among 7 conditioned dogs, severe hearing disorder was observed in one, medium in 3 and slight in 2. One dog didn't show any hard of hearing at all.
2) DHSM 50 mg/kg vitamin B1 2 mg/kg a day and DHSM 200 mg/kg vitamin B1 10 mg/kg a day was applied for the 2nd group and the 4th group, respectively. No difference could be observed between these two groups. In the comparing audiograms before and after the use of dihydrostreptomycin, only 0-10 db change in all frequency area was perceived and the hearing disorder did not appear at all.
3) In the first part, observation for long term was made on the clinical cases before, during and after the simultaneous application of DHSM and vitamin B₁.
Summarizing the result in the first part and experiments on animals in this part, the author concluded that hearing impairment caused by DHSM can be prevented by the combined use of vitamin B1 at the time of DHSM application.

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The basic investigation of the paranasal sinuses, especially on the form and the vascular system of the maxillary sinus of rabbit was performed for the purpose of getting some findings before the experimental studies with the animal.
1) The maxillary sinus of rabbit is divided into four parts ; the superior -and inferiorpart of the nasal sac, the anterior-and posterior part of the proper maxillary antrum.
2) The author persued the passage of the arterial system by means of injecting artificial resin into the vascular cavity, and found that the arterial system which distributes around the maxillary sinus, about which no detailed description has been done, is composed of, besides arteria sphenopalatina, also the branches of arteria infraorbitalis, being both of them the branches of arteria maxillaris interna.
3) By experimental injection of stain into the vascular cavity, to investigate how to attain the highest concentration in the maxillary sinus through the carotid artery system.
By use of the ligation of unnecessary branches of the artery except the internal maxillary artery, author proved that one can get twice or more as much concentration of the substance in the maxillary antrum.

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