The tuning fork tests may have been forgotten since the modern audiometry developed. In this paper, the authers described their own data of tuning fork hearing tests, and the literature on the use of tuning forks in the audiometric era were reviewed and discussed from the viewpoint of clinical otology. And it was concluded that, even in the era of sophisticated electronic hearing tests, the use of tuning fork in the daily clinical practice is still far from outdated.
The effects of repetitive transcranial magnetic stimulation (rTMS) on auditory brainstem responses (ABR) and middle latency responses (MLR) and on neuroanatomical structures in the auditory tract in rats were investigated before and after 1 week exposed to 2010 stimuli at 25Hz repetitive train pulses transcranial magnetic stimulation level (1.6 tesla instrument output) with a magnetic coil positioned over the cranium. (1) The mean latencies and amplitudes of ABR of the positive waves P1, P2, P3 and P4 showed individual changes in exposed rats, but the changes in the latencies and amplitudes by rTMS were statistically insignificant. (2) The mean latencies and amplitudes of Na, Pa and Nb of the post exposed MLR were not significantly different from the pre exposed. Light microscopic examination of the cochlear nucleus, brainstem sections and cortex of temporal lobe possible which are sources of waves of the ABR and MLR, showed no rTMS-related changes in cellular organization or histological damage. In conclusion, no deleterious effects of rTMS were observed on the peripheral and central auditory system of rats after high-frequency repetitive train pulses transcranial magnetic stimulation.
To search for mutations in mitochondrial genomes among the out-patients with hearing impairment, we investigated the mutations, A1555G, A3243G, A7445G and 7472insC of the mitochondrial genome. Five out of 160 patients, one with the A1555G mutation and four with the A3243G mutation, who comprised approximately 3% of the total patients had a mutation in their mitochondrial genome. The clinical features of these 3 patients are shown.
Acute low-tone sensorineural hearing loss (ALHL) has been considered as a clinical entity characterized by 1) unknown etiology, 2) sudden onset of low-tone sensorineural hearing loss, and 3) without vertigo. The prognosis of ALHL has been reported to be good. In this paper, we reported 2 cases of ALHL whose hearing loss progressed to profound hearing loss. The clinical features of the cases included 1) middle aged male, 2) cochlear hearing loss, and 3) no response to glycerol administration. Both cases showed autoantibodies, but their hearing loss did not respond to the administration of steroid hormone. From these features, the pathophysiology of hearing loss in these patients was considered different from that of cochlear Meniere's disease or autoimmune sensorineural hearing loss. Further investigation will be needed to clarify the pathophysiology of this clinical entity.
Effectiveness in speech reception of the frequency-shifted words was evaluated in the elderly persons with sensorineural hearing impairment and using hearing aids. The subjects were 11 persons (including 2 females) with the mean hearing levels between 46dBHL and 83dB HL. The word intelligibility was measured under environmental noise level of 45-50dB (A) and speech sound level of 70dB (A) at the listening position 2 meters apart from a loud speaker. Two sets of 50 words, one was of ordinal pitch range and another was of very high pitch range, uttered by female narrators, were used for this evaluation. Each word set was modified it's pitch frequency and spectral envelop simultaneously up and down, that is frequency-shifted, by every one fourth octave. All subjects heard all modified word sets. Consequently, it was considered that the frequency compression for high voice was effective in improvement of word intelligibility and there would exist the frequency range where all subjects felt easy to listen. However, it was suggested that the frequency shift of wide range would cause perceptible voice character changes. Further, it was suggested that the pitch frequency of speech materials for auditory test would possibly influence to the test results.