PURPOSE: To obtain the design logic which brings an ideal flat characteristics, by the process of manufacture, by measuring and recording the waveform of various raw sounds, leaving the components in matching with that of playback audio wave and removing those not in agreement.

CONSTITUTION: Speakers making direct sound, detour reflection sound, and detour echo sound used for an audio device reproducing the raw sound field with feeling of cube are purchased with the critical design, and the waveforms for various raw audio waves are measured and recorded with fidelity. Further, high and low tones in which the waveform of reproduced waves are in agreement with various raw sounds are left according to a given tuning theory, the components not in agreement are removed with the tuning logic, to form the audio device. Further, the frequency characteristics of the audio device can be made ideal from the high to low tone regions.