Abstract
The tympanic membrane is one of the high speed vibrating organ in a body as well as the vocal cord. It is suspected that hemodynamics in it is different from that in the other organs. No documentation, however, has been available concerning this presumption.
The purpose of this study is to investigate peripheral blood flow characteristic to the tympanic membrane which is a high speed vibrator.
The experiment was performed on 82 guinea pigs which were exposed to various levels of sound. The changes in blood volume of the tympanic membrane were estimated by Benzidine staining after momentary fixation with liquid nitrogen during sound stimulation. Furthermore, the blood volume of the tympanic membrane was measured by counting radioactivity of R. I. S. A. which had been injected prior to sound application.
The results obtained were as follows.
1) The blood volume in the tympanic membrane decreased with increasing sound intensity.
2) The greatest blood volume value was observed under quiet circumstances C 0 phon).
3) Following the application of sound, the blood volume was first reduced around the intermediate region which vibrated most violently. The blood volume was then decreased near the anulus of the tympanic membrane.
4) The results obtained by two different experimental technics mentioned above showed almost the same tendency.
5) The blood volume in the tympanic membrane was almost the same for different pitches at a given intensity level (70 phon), except for 8000 and 500 Hz: it was slightly greater for 8000 Hz and occasionally (in one of six animals) less for 500 Hz than for other pitches.
6) The results support that the blood volume in the tympanic membrane is affected by physical factor such as a high speed vibration.
