| 摘要 |
PURPOSE:To improve the resolving power of the locating of a sound source by changing the relative positons of a sounding body and a sound-receiving device in timing and thereby conducting frequency modulation of the sound. CONSTITUTION:A sound souce 1 mounted on a rotating disc 7 comes near to a sorface 3 to be investigated, where the former turns vertical to the latter, once in one rotation of the disc 7, and this timing is detected by a rotational position detector 8. The signal of this detection is impressed on a computer 6 together with a hologram information delivered from an analyzing device 5 according to electric signals accompanying the catching of a sound by a moving microphone 2 and a standard microphone 4 which make sampling on the surface 3 at a fixed interval, and diffraction counting is made by the computer. On the occasion, a noise delivered from the sound source 1 and having a frequency f1 is modulated in its frequency by Doppler effect to be a frequency f2 based on FormulaI, and the resolving power becomes C/4f2, i.e. twice as large as that in the case when the relative positions are not changed in timing. In this formula, C is the velocity of sound in air and V is the average velocity of approach of the sounding source. |
