Although many investigations about microcirculation of the cochlea have been reported, less knowledge such as blood volume or blood supply of each turn has been obtained. This study was originated to find out dynamic blood supply to each turn of the guinea pig cochlea. Points of study were as follows: 1) Distribution and numbers of the radial arteriole of each turn with the use of India ink. 2) Blood volume determination of each turn with the perfusion of 10% Evan's blue, and the ratio of blood volume and dry weight of each membraneous cochlea. 3) Blood flow speed of each turn indicated by numbers of running leucocytes in radial arteriole for one minute. The results obtained were as follows: 1) Radial arterioles of 5 to 6 in apex turn, 9 to 13 in 3rd turn, 17 to 22 in 2nd turn and 33 to 40 in 1st turn were observed. The ratios of radial arteriole's numbers of apex, 3rd, 2nd and 1st turn were 1.0, 2.0, 3.6 and 6.7. 2) The ratios of blood volume in apex, 3rd, 2nd and 1st turn were 1.0, 2.2, 6.7 and 16.6. The 1st turn was really rich in blood volume, though which was less than 0.1μl. On the other hand, the dry weights of membraneous cochlea of each turn were 30γ in apex turn, 48γ in 3rd, 62γ in 2nd and 85γ in 1st. The ratios of blood supply per dry weight in apex, 3rd, 2nd and 1st were 1.0, 1.4, 3.2 and 5.9, which were similar to that of radial arteriole in each turn. 3) The mean number of running leucocytes in radial arteriole for one minute was 62 in apex turn, 31 in 3rd, 48 in 2nd and 64 in 1st. The dynamic blood supply in every turn of the cochlea will be considered in consequence of the studies about numbers of radial arteriole, speed of blood flow and blood volume per tissue weight. The ratios of the dynamic blood supply in apex, 3rd, 2nd and 1st turn were 1.0, 0.7, 2, 6 and 5.9. Therefore, it was concluded that the dynamic blood supply of 1st turn was six times higher than that of apex.
As a part of the study of perceptive deafness the experiment is being made with the simulation of the inner ear deafness. The simulation consists of an electronic equipment with a distortion circuit and a normal hearing person as a detector. The conditions for the simulation of the inner ear deafness in this experiment are: 1. the rise of the threshold of hearing, 2. the low articulation score, 3. the presence of recruitment, and 4. the hearing difficulty under noisy circumstances. The experiment was carried out concerning the recruitment phenomenon, and the following comments were made: 1. The non-lineality of the input-output intensity as such does not bave much influence upon the articulation score. When the wave form is distorted, the articulation score lowers. 2. The recruitment phenomenon is clearly observed when the maximum loudness level is close to that of the normal ear. 3. It is suspected that the inner ear impairment is not severe when the recruitment appears at the small loudness level.
It is not an easy task to find out the fundamental causes whether or not the hindrance to the power of expression of a cerebrally palsied infants really due to the paralysis on the limbs movements, or due to speech impediment, or because of the accompanied hearing loss, or mainly due to the delay of his mental development. Many reports have been made by those reporters as Taguchi (1958), Imanishi (1960), Hiroto (1956), Byers (1955), and Fisch (1955) to the effect that cerebral palsy very offenly causes sensitive hearing loss. However, only few researches have been done in the field of infants. This time, at the Tokyo Infant Nursing Hospital, we conducted audiometry to those infants who had been suffering from considerable heavy cerebral palsy, and had diversified study regarding the frequency of the accompanied hearing loss in cerebral palsy, relation between the type of cerebral palsy and the hearing loss, and the difference of mental development profil due the existence of difficulties in hearing.
As a result of inquiries as to the impressions about the experience of the hearing aid to the deaf who visited the better hering clinic of Kobayashi Institute of Physical Research, it has been concluded that the deaf can not carry conversation as satisfactory as they wish even with a hearing aid. As to the desires of the deaf, the mild deafness “want to be able to carry conversation as well as normal persons and the heavy deafness” want to be able to hear somehow. As to the length of time spent with the hearing aid, there was no relation observed between that and severity of deafness but necessity of conversation. The deaf always want better hearing aid to be able to carry conversation smoothly. Although, at present, such an ideal hearing aid as they want has not been produced yet. So that there is no way but auditory training accompanied with a hearing aid for the deaf. The auditory training has been given to the acquired deaf in our institute for more than three years. The main subject of the auditory training here was the lip-reading method with a hearing aid, but this method has not been very effective. A reason was that the appointment of a good auditory trainer had been not been available and the other reason was that the deaf soon got tired of training because of its' simplicity. A new method of auditory training using Video-corder has been devised in our institute recently. A Video-corder is an apparatus which can reproduce recorded sounds and pictures simultaneously. So that the deaf can train lip-reading themselves by using this apparatus whenever they want. The effect of this new method is not known yet as this has been just started, but a prospect of a good result can be expected. It is desired that this new method accompanid with lip-reading method would be introduced and employed at any district of the country.
The shift of uncomfortable loudness level in ears with loss of hearing were investigated. In most of ears with sensori-neural hearing loss was the uncomfortable loudness level found to be unchanged or even lowered, in spite of the raised air conduction threshold. The raised uncomfortable loudness level was observed in the ears with very profound hearing loss, and with retrocochlear lesions. In the latter case, hearing loss was found not necessary to be severe. The case of hyperacusis without hearing loss showed the lowered uncomfortable loudness level, and the fluctuation of the level was found paralel to their complaints. In many ears of sensori-neural loss the speech discrimination scores were found dependent upon the range between the uncomfortable loudness level and air conduction threshold. The ear with central lesion was exceptional. A presented case, once thought having conductive hearing loss, was found to have an erroneous bone conduction due to the incomplete masking, and the measurement of the uncomfortable loudness level disclosed the patient's sensorineural hearing loss.
A. We classified them (all member 5410 ears) to seven groups and obtained the statistic mean and deviation of increasing hearing loss according with that of their age and carier of each group. B. Workers group in industrial noisefull factory (1 st group, repairing the paste of airplane) showed the most heavy hearing loss. Their hearing loss suddenly increased on later half period of their thirty years old. C. On groups exposed to direct air plane noise (noise observed in the field near the airplane), 1) workers in rump, 2) tester of machine parts of airplane, 3) guard and officer in airport 4) passenger of cargo showed lowered hearing loss than the first group, but occuring points of the increasing tendency are same to that of 1 group. The curve of pilot and co-pilot group showed almost same tendency but lower increasing tendency. Perhaps, a part of this group (over 8, 000 hours in airplane) showed suddenly increased hearing loss (specially in high frequency and speech range). Tendency of hearing loss of the group of steward and stewardess group in same as ordinary persons. These who always put on the earplag or ear maff in workers exposing the noise of airplane, increasing tendency of hearing loss is lower than unused groups of them.