相関法による進行・逆進行音波の実時間分離測定法

抄録

This paper describes a method for separating in real time each of progressive and retrogressive spatial sound waves directly from the reflective sound field by using a correlation method. A spatial sound wave implies a spatially distributed sound pressure oscilation, that is, a sound wave group which travels backward and forward between the sound source and the reflector as time elapses. And, it can be equivalently expressed and measured in the form of a correlation function obtained from the sound source and receiver signals in the case of scanning the receiver position(variable)and fixing time delay(parameter). In order to realize the real time separation, the simultaneous scanning both of time delay and receiver position is proposed. Each of progressive and retrogressive spatial sound waves is extracted by scanning time delay with positive and negative time delay ratio respectively, together with scanning receiver position with constant moving velocity. And, their travelling distances are decided proportional to the initial time delay. Some experiments based on the theory are carried out. Then, considering about the sound waves concerning travelling distance and direction, attenuation by distance and wavelength, it is shown that the theory and procedure of the method for separating is valid.