The purpose of this study was to explore the effects upon auditory sensitivity and discrimination, and to investigate the relationship between the several tests used in the evaluation at advanced ages. The speech reception threshold and the speech discrimination were tested with the Japanese test material List 57 AB. A comparative analysis of the articulation scores of the voiced and voiceless consonants revealed some interesting differences in the discrimination function. The results obtained were as follows: 1. Auditory discrimination was generally poor when compared with pure tone hearing in presbycusis, but several cases showed better response for speech. Consequently, we considered the possibility of the auditory compensation in the brain for the speech hearing impairment. 2. In presbycusis the threshold for the voiced consonants was many times somewhat better than that for the voiceless consonants, although the maximum discrimination score was better for the voiceless consona nts. 3. The average articulation curve in presbycusis showed less steep than normal slope. It was significantly less steep in the severe cases. 4. In environments of noise, loss of hearing due to presbycusis resulted in severe loss of discrimination of speech, particularly of voiceless consonants.
Speech audiometry and noise speech audiometry are practiced on higher aged men. Those tests are done on satisfactory conditions as follows. 1. 70 years old over. 2. Horizontal type on speech range in pure tone audometry. 3. They have all sign of cerebral arteriosclerosis and now lied an hospital or aftercare house. Results of those tests are presented as follows. 1. S. R. T. and threshold of articulation score are located right than normal people, but distance between S. R. T. and articulation score was no difference compared with young men. 2. Diminishing ratio of speech in noise audiometry of higher aged men is larger than young men.
Speech hearings of 57 presbyacusises using Japanese test material 57A were examined in comparison with 39 cochlear deafnesses and 6 retrocochlear deafnesses. The author examind relation of pure tone hearing loss and SRT and discrimination loss, relation of discrimination loss and hearing span. The conclusion were as follows 1) Generally, SRT of presbyacusises were relative to their pure tone hearing losses, but both deviations were extended extremly. 2) Discrimination losses of presbyacusises were various in relation to their pure tone hearing losses, but discrimination losses of presbyacusises were classified in a cochlear type and a retrocochlear type. 3) Hearing spans of presbyacusises were various in relation to their discrimination losses, but hearing spans of presbyacusis were classified in a cochlear type and a retrocochlear type.
In totally 1, 189 “Human Dock” patients mainly composed of 40-49 and 50-59-year-old male group, 402 normal hearing persons and 135 presbyacusis were found. Then, blood pressure, serum cholesterol levels, retinal blood pressure and retinal angio-sclerois of presbyacusis group were compared with these of normal hearing group. The results of these statistic observation are as follows. 1. Presbyacusis is related to both systolic and diastric blood pressure. 2. But, serum cholestrol levels are not related to presbyacusis. 3. Both retinal blood pressure and the degree of retinal angiosclerosis (Keith-Wagener) are apparentry related to presbyacusis. 4. Mean audiograms of hypertonic presbyacusis group aged 40-49, shows about 10-15dB more hearing loss at 4000Hz and 8000Hz than those of hypotonic group same aged, but these differences of both group aged 50-59, are more small. 5. Hypertension and angiosclerosis are sure to cause presbyacusis early and to progress it fast. But, the mutual relation of presbyacusis with hypertension and angio-sclerosis is remain unexplained in persons of more abvanced age. 6. It is unquestioable to be other pathogenic factors of presbyacusis than circulatory disorders in inner ear, environmental noise is seems to be one of important other factors.
This report is the results of audiometric observations of hearing disorders on diabetics in cooperation of the members of Tokyo diabetic society. The numbers of cases were amounted to 109 cases selected at discretion. Consequently, the perseptive deafness including the insensible deafness account for 48 cases of all. And this result is excepted from non-diabetic factor. It is the characteristic sign that those audiograms are almost symmetric and the recruitment phenomenons are showed positive. The hearing drop on 8000c/s is distinguished. It is found that, high ton dropping type is increased in short term suffering, degression type or horizontal type is increased in long term suffering. From these facts, it is suggested that perceptive deafness on diabetics is progressive. On the case with diabetic neuropathy, the perceptive deafness is distinguished in hearing drop. In addition, many perceptive deafness are found in the cases with diabetic retinopathy. From these facts, it is suggested that fundamental and pathological change of inner ear is concerned with that of retina. Further more, concerning with therapy of diabetes, the perceptive deafness is found in many cases treated by insulin. And this suggest that hearing drop is concerned with controls of diabetes.
Using histochemical technics, the human temporal bone of aged people were studied in regard to 1) distribution of capillary in the spiral lamina, 2) loss of the nerve fiber in the spiral lamina, and 3) pathology of the basilar membrane. 1. The capillary was visualized by alkaline phosphatase staining. Density of the capillary network was less in the lower basal turn. Distribution and density of the capillary, however, seemed not to be altered throughout the life. 2. Near the basal end, the afferent and the efferent nerve fibers were missing in the spiral lamina as well as in the organ of Corti. The morphological changes and the loss of the nerve fiber were lesser toward the apex. Another type of the nerve fiber loss was that the fiber was missing diffusely throughout the cochlear turns. 3. The basilar membrane showed lipids deposits in pars pectinata of the lower basal turn. The lipids consisted of neutral fat and cholesterol. Its significance was discussed from the view point of sound transmission. The author would like to propose “Lipidosis of the Basilar Membrane” as a new histopathological type of presbycusis.
Presbycusis is one of the most interesting problem in gerontology. But the exact nature of it is still obscure. The author examined the temporal bones and central auditory pathways of 105 autopsy cases of which 35 cases were checked audiometrically before death, and compaired functional and morphological data with reasonable acuracy. The most conspicuous pathological findings obtained were spiral ganglion atrophy, cerebral degeneration i.e. softening, and lumen narrowing of internal auditory artery. The types of hearing loss in presbycusis coincided well with the spiral ganglion atrophy, and “level down” of auditory acuity in whole frequency range was supposed to be due to the effect of cerebral degeneration. The significance of senile atrophy and arteriosclerosis on the development of presbycusis was discussed.
Hearing of the elderly people who showed almost normal pure tones thresholds below 1000Hz was discussed. Filtered speech (1200Hz low pass) test, speech test using synthesizede vowels and directional hearing test were used for the analysis of the hearing. These elderly people had good discrimination scores for the synthesized vowels of which the duration was only 16msec, 24msec (2 or 3 foundamental waves), or whose F1 and/or F2 was shifted from the original positions, on the other hand poorer results than those of the young people were obtained in the filtered resonants (1200Hz low pass). It was suggested that those results were related to the decrease in number of ganglion cells of the central nervus system. A coding and decoding system and its distortion seen in the retrocochlear lesion were demonstrated using a model.
The purpose of this investigation is to determine the correlation between the pitch discrimination and speech audiometry for an advanced age group. In this study subjects are composed of thirty untrained aged men from 66 to 81 years. The experimental method is in principle similar to the A-X method employed by other investigation, however the arrangement of test tones is different from the A-X method. Two kinds of test tones are arranged irregularly: 1) the reference signals (A) which are maintained constant, 2) the variable signals (X) which frequency are slightly different from the reference signals. Subjects are required to detect the variable signals among the reference signals. Even untrained old aged subjects are able to understand this method. This method seems to be more adequate for the pitch discrimination test of untrained subjects than the other. The following results were obtained: 1) The values of pitch discrimination in advanced age group are larger than in the young group. 2) In advanced age group obvious relation between the pitch discrimination test and the speech discrimination test could not be demonstrated. 3) It drows inferences from the above mentioned facts that the function of speech discrimination is so complicate, and the picth discrimination is nothing but a part of this function.
Presbyacusis is a kind of hard of hearing which every body takes but there are many stages in severity. There is no other way of curing it except the use of hearing aid. Many who use hearing aid all day are usually found in a group with hearing loss more than 50dB at low tone, and also many who use it some times are mostly found in a group with that less than 50dB. There are many of those with hearing loss more or less than 50dB who do not have will to use hearing aid because of troublesome in using it. Many of those using hearing aid all day do not use only it becausse of the reason that they can carry conversation easier but because they can manage to catch the voice with it when they are not able to hear the tone without it. Therefore, there is a tendency that many deaf with more severe hearing loss than the so-called indications of hearing aid often use it. The harder the hearing loss has the more the necessity of hearing aid and the more times of using it. Even with the hearing aid, some of the persons with severe hearing loss can not carry conversation easily from the beginning, auditory training makes it possible. The most of the deaf less effective with hearing aid need a longer period of auditory training. In order to decide the indications for use of hearing aid, effectiveness of hearing aid in the individual should be judged first of all and his own will and the co-operation of his surrounding for auditory training have to be judged at the same time.