音の前後感覚に関する基礎的ならびに臨床的研究

抄録

1) Amoung the earlier studies on the directional hearing, there have been few on the discrimination ability of the sound from front and rear sources(DFR).Foundamental study on this ability was performed to establish the test method, and various kinds of hearing disorders were tested.
2) The method was as follows:
Two loudspeakers were set in front of and in the back of the subject at the same distance.
Pure tone, white noise and bandpass-noise of the same loudness were given from the two speakers.The subjects were told to answer where the sounds came from.
3) When a subject kept his head still.
i) The wider the frequency range of the testnoise, the better the DFR.
ii) To elicit good DFR, the duration and the intensity of the testnoise should be more than 0.25sec and 40db(SL) respectively. DFR was not significantly influenced by the rise and decay time of the testnoise.
iii) Concerning the azimuth of the sound sources, the best DFR was obtained when the sources was 30° to 45° apart from the median sagittal plane.
iv) When earplugs were inserted in the both earcanals, DFR was disturbed, but the effect of auditory fatigue was not so remarkable as earplugs.
4) When the head of subject was moving, narrow bandpassnoise was also well discriminated as whhite noise.
5) DFR of the subjects with hard deafness was oor in proportion to the degree of hearing loss.
6) DFR was poor in the presence of central disorders, even when the hearing was normal. The last result indicates the possible usefulness of he test as a diagnostic aid of central disorders.