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Abstract

A wide frequency range signal from a test sound source is reproduced successively by a plurality of speakers, and the reproduced sound is detected by a plurality of microphones, after which the frequency characteristics are obtained at FFTs, while obtaining the frequency characteristics of the wide frequency range signal at an FFT. A high frequency range level is normalized with a low frequency range level, and a determination section compares the normalized value with a reference value stored in a reference value storage section to determine the number and positions of people in the sound field. The transfer functions between the speakers and the microphones are calculated at transfer function calculators, and impulse responses are obtained at IFFTs, after which a reverberation time calculator calculates the reverberation time based on the impulse responses. An audio signal is adjusted based on the results.

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First Claim