1980 年 36 巻 4 号 p. 194-198
In this paper, an analytical technique for calculating the amplitude of reflected sound waves from a cylindrical target of finite length is treated. Both sound source and receiving point are assumed to be located at the same position, apart far from the target. The approximate formulas for the reflectivity are derived under certain geometrical restrictions. The reflectivity is termed as the "directional sound reflectivity of the cylindrical target", which is defined as the ratio of the sound pressure of the reflected wave from a target to a certain pressure which is to be calculated based on the theory of geometrical optics. To verify the validity of the approach, some experiments were performed in air at the frequency of 39. 00 kHz. The results qualitatively agree with the calculated ones by the present method. This confirms the usefulness of the present technique to calculate the reflection of sound waves from a cylindrical target.