The loudness recruitment phenomenon is valuable to differentiate the cochlear deafness from the conductive and retrocochlear lesions. There are many recruitment tests, i.e. balance test, DL test, SISI test, etc., which are performed routinely in many clinics. However, some cases cannot be tested satisfactrily, because these tests require trained subjective judgement of examinee to the complex sound stimuli. From this standpoint, a new objective test for recruitment phenomenon by the evoked response to DL and SISI stimuli has been contrived. Forty-one cases were tested. Their ages were from 16 to 66 year-old. They were of 20 normal hearing, 3 conductive deafness and 18 perceptive deafness among which 3 retrocochlear deafness were included. Tone stimuli were DL or SISI, the increment of which was 0.2 to 5.0dB at 10dBSL and 30dBSL. The tone frequency was either 1000 or 2000Hz. The increments had a rise-fall time of 50msec and a duration of 1sec in DL or 200msec in SISI. Sixty increments were presented in every test run. The minimal size of DL was determined by the evoked response at the two hearing levels. There was no difference between DL and SISI stimuli in the threshold of evoked response. The sizes of DL were as follows; 3.8-5.0dB (mean. 4.5dB) at 10dBSL and 1.8-4.0dB (2.8dB) at 30dBSL in normal hearing, 3.8-4.0dB (3.9dB) at 10dBSL and 2.8-3.2dB (2.9dB) at 30dBSL in conductive deafness and 1.0-4.0dB (2.4dB) at 10dBSL and 0.8-2.8dB (1.9dB) at 30dBSL in cochlear deafness. Three cases, suspected the retrocochlear lesions showed nearly the same DL sizes as those of normal hearing. From those observations, the following criteria of the objective test of recruitment were considered: (1); When the size of DL at 10dBSL is smaller than 3.0dB and the difference of the size between the two hearing levels than 0.6dB, recruitment is positive. (2); When the size is between 3.2 to 3.8dB at 10dBSL and is smaller than 1.0dB in the difference, recruitment is questionable. (3); The others are negative. In fact, 85% of cochlear deafness were decided as positive case. Meanwhile, the subjective recruitment tests showed 64% as positive. According to these results, the newly developed method is considered as usefull for an objective test for the recruitment phenomenon.
The follow-up retest of hearing change and vestibule function test were performed on the patients of Tokyo Diabetic Society. Among 58 cases of perceptive deafness in 127 cases tested 3 years prior to the retest, only 38 cases were possible to do the follow-up retest. All examples were exclusive of non-diabetic factors. On the retest, 27 cases in 38 cases showed hearing change in the 3 years interval. The hearing of the 27 cases mostly fluctuated and progressed to the advanced hearing loss. The vestibule function test was performed on 55 diabetic cases. Out of 55 cases, 46 cases showed perceptive deafness and 9 cases showed normal hearing. As the results, spontaneous nystagmus were positive in 6 cases and an abnormal response to caloric tests were accounted in 22 cases among 46 perceptive deafness cases and 4 cases among 9 normal hearing cases. In either case, there was not much difference of caloric response on the both side. As a whole, a lowering of reaction was conspicuous. In the conclusion, the inner ear disorder of diabetic patient was caused by morbid of the inner ear blood vessel and nerve atrophy or degeneration, if any, might be a secondary change.
In 46 adults with sensory hearing disorder of over ten years' duration, test results of their speech discrimination were analysed and following points were discussed. 1) From the data of speech training in the deaf children, Kubota and others reported that their development of the vowel /i/ articulation is mostly disturbed in vowels and their consonant /r/ articulation developed poorer than /b/, /d/, /g/. While, in the present study, it was shown that deaf adults discriminate the vowel /i/ easily than other vowels, and the consonant /r/ than /b/, /d/, /g/. From their discrepancy it was assumed that the developmental disturbance of both /i/ and /r/ articulation in the deaf child does not depend on hearing oss, but on the difficulty of /i/ and /r/ pronunciation. 2) The patients with the same discrimination scores were divided in two groups, i.e., patients with high tone loss and with flat audiogram. In the vowels' discrimination, the latter showed poorer results than the former, and the oposite relation was observed in the consonants' discrimination. 3) A mis-heard consonant largely distributes in its group consonants and in this paper it was discussed that value of mis-perception in unrelated consonants should be distinguished from that of the confusion in its own group. From this point of view, a new confusion matrix for each case, in which the misperception in related consonants were valued as correct answers, was composed and discrimination scores and transmit information were calculated. In comparison between the patients with high tone loss and with flat curve, the former shows lower score of transmit information than the latter, even with the same discrimination score. 4) Paired comparison method for speech hearing test was shown. for example: misperception test for /m/, /n/ group. Eight paired test signals, /m/-/n/, /m/-/k/, /m/-/m/, and /n/-/m/, /n/-/r/, /n/-/k/, /n/-/n/ are given to a subject and the subject is indicated to answer successively whether to speech sound are same or different. From their answers, the degree of /m/-/n/ confusion, /m/-/n/-/r/, and disability of discrimination of /m/, /n/ group will be known.
After isolating the tectorial membrane of whole coil or each turn, measurements of them were carried out. The best way of measurements was found to observe in saline solution after fixing by neutral 10% formalin. The results obtained were as follows: 1) Total length of the tectorial membrane was 18mm. 2) The most widest total width including limbus and tectorial part was second turn. It was 244±9.2μ. 3) The width of the tectorial part was 45±5.5μ at hook end, 114±7.5μ at basal turn, 128±4.6μ at second turn, 134±5.4μ at third turn and 135±5.5μ at apex respectively. The width of the tectorial part increased from hook to basal turn abruptly, after which it increased gradually. The tectorial width of the apex showed 3 times as wide as hook end. 4) It was observed by differential interference microscope that the thickness of the tectoiral membrane-increased from apex to base gradually. The difference of each coil of the tectorial membrane was also observed. 5) The shrinking of the tectorial membrane after alcian blue staining implied that the observation of the tectorial membrane in physical condition was impossible by ordinary histochemical technique. 6) The change of the width of the tectorial membrane in proportion to that of basilar membrane implied that the tectorial membrane participated physically in hearing mechanism.
Ten samples of the averaged spontaneous brain activity were made on a sleeping child of 5 years old. On the other hand, from a typical pattern of the averaged evoked response, 5 samples with different amplitudes were prepared. Then each of the 10 samples of the spontaneous activity and each of the 5 samples of the evoked response were composed by using an averaging computer. Two trained examiners independently made the determination of the presence or absence of the evoked response on 41 out of 50 composed samples and 10 samples without evoked response. The decision was also attempted according to an objective standard made by one of the authors. Besides, peak latencies of P2 and N2 as well as P2N2 amplitude were measured on 19 composed samples. Results obtained were summarized as follows: 1. There was an individual discrepancy between the examiners as to the detectability of the response. 2. False positive decision occured in about 10 to 35 per cent of the judgements. 3. Almost 100 per cent detection of the response Was achieved when the amplitude of the evoked response was twice as large as the levels of the averaged background activity. 4. The range of so-called “trasition zone” of the evoked response was estimated to cover the range of the stimulus intensity of 40 to 50dB or more. 5. The latencies and amplitudes of the evoked response were modified considerably by the background activity.
A 22-year-old female with typical Treacher-Collins syndrome had an antimongoloid slant of the palpebral fissures, hypoplasia of the malar and mandibular bones, and external acoustic meatuses of pediatric ear speculumpatency. On otoscopic examination, no handle or short process of a malleus, or light cone was seen. The ear drum consisted of thin, purplish-red, membranous tissue showing no differentiation of pars tensa and flaccida. Audiogram showed a typical conductive deafness. Tympanotomy of the left ear disclosed virtual absence of the tympanic cavity with an osseous plate adherent to the tympanic membrane. There was a rudimentary malleus and incus, but no stapes, oval or round window were seen. Postoperatively, a slight improvement in auditory acuity was achieved. This was probably due to the removal of the osseous plate. The patient became possible to use a hearing aid. The present case was compared with other operated cases in Japan, and the anomalous tympanic cavity was discussed from an embryological point of view.
The present experiment was made to evaluate the ototoxicity of tuberactinomycin-N (TUM-N) in long-term administration to the Hartley strain guinea pigs (300g body weight at the start of the experiment) and the ototoxicity was compared with those of capreomycin (CPM) and kanamycin (KM). TUM-N was given to 4 guinea pigs at dosis of 200mg/kg/day intramuscularly for 6 months, and CPM was administered to another 4 at the same dosis for the same period. KM was injected into the remaining 5 at the same dosis intramuscularly for 3 months. Pinna reflex test was performed before, during and after the injection of the antibiotics by audiometer. All of these animals were killed after the end of the experiment and their temporal bones were removed after intravital fixation. Horizontal serial celloidin sections were stained with hematoxylin-eosin and then investigated microscopically. 1) Pinna reflex test: The loss of the pinna reflex occurred in the frequency range from 8, 000 to 10, 000Hz in 50% and in the total fraquency range from 250 to 10, 000Hz in the another 50% of the CPM treated animals. The loss of the pinna reflex was detected in the total frequency range in 100% of the KM injected animals. However, there was no animals with the loss or increased threshold of the pinna reflex in the TUM-N treated animals. 2) Histopathologically, 50% of the TUM-N treated animals showed the irregular loss of the outer hair cells of the organ of Corti confined to the basal end of the cochlea but the another 50% did not exhibit any remarkable pathologic change of the organ of Corti. In the CPM treated animals, extensive loss of the outer hair cells extending from the basal end to the more upper part than the 2nd turn of cochlea was found in 75%. However, the loss of the outer hair cells was localized in the basal end in the remaining 25%. The KM treated animals showed the more extensive loss of the outer hair cells in 100%. 3) These results indicate that TUM-N has the most mild ototoxicity among the antibiotics used in this experiment.