結合音現象からみた内耳機能の解析
1986 年 29 巻 3 号 p. 199-212
詳細
1986 年 29 巻 3 号 p. 199-212
Characteristics of the combination tone 2f2-f2 in the human ear-canal sound pressure were investigated with a spectrum analyzer.
1) Non-linear wave equations showed that the combination tone 2f1-f2 results from a third-order (cubic) non-linearity, and L (2f1-f2) is determinedby L (f1) 2L (f2).
2) From the results of these investigations, it seemed clear that the combination tone 2f1-f2 is not generated in the experimental apparatus, in the external ear, in the eardrum, but in the cochlea or the more central pathway.
3) The growth of the 2f1-f2 level with increasing stimulus level can be divided into two ranges (slope near 1, and slope near 3).
In the range of the slope near 1, it was assumed that an active process of the inner ear affects the vibration of the basilar membrane and has some relationship to the generation of the 2f1-f2 tone.
4) The 2f1-f2 level decreased gradually with increasing frequency separation of the primary tones.
5) In patients of mumps deafness, the 2f1-f2 level was reduced at the low stimulus levels (L<90dB). But the 2f1-f2 level was not affected by a threshold dip.
