A correlation relationship operating section 26 obtains a correlationfunction C_A,B(τ) related to the time between the two points of the measurement point A and the measurement B using the history of the acquired sound pressures. 取得した音圧の履歴を用いて、相関関係演算部26は、測定点Aと測定点Bの2点間の時間に関する相関関数C_A,B(τ)を求める。 - 特許庁