PURPOSE: To simply and accurately realize a sound field in all the positions of all shapes by making the reduced model of a shape desired by a listener, measuring the impulse response with an ultrasonic wave, converting it to a digital signal and transferring it to a sound field reproducing device.

CONSTITUTION: At first, the solid of a reproducing space wanted to listen by a listener or a shape of a plane is made with a reduced shape model 1 and an ultrasonic oscillator 4 and a mike 5 are respectively set to a speaker position and to a listening position in it. Next, an impulse for an impulse response measuring is generated from a generator 2 and reproduced from the ultrasonic oscillator 4. The reproduced impulse response is measured with the mike 5 and after being amplified to a suitable size by an amplifier 6, converted to a digital signal by an A/D converter 7. In the figure, the impulse response measured by this method is shown. In an arithmetic part 8, based on this digital signal, an initial reflecting sound to be a characteristic or an attenuation coefficient is extracted and transferred to a sound field control device 10 by a data transferring device 9.