直方体残響室における2点間音圧相関係数
Point-to-Point Correlation Coefficient of Sound Pressure in Rectangular Reverberant Room

Mikio Tohyama, Akira Suzuki, Shokichiro Yoshikawa
1977 Acoustical Science and Technology  
エnth 量 s paper , the corre 且 ation coe 伍 cient of sound pressure in a rectangular reverberant room is studied . The results of nu 皿 erical ca ! culations at lower fre− quencies are compared with the experimental ones , alld the relation between the geometric acoustics and the wave theory is also mentioned . We consider the sound field in the room excited by narrow band コ oise . According to Morrow , s ass1 ユmptions5 } , the mean ( time −averaged ) square pressure distr 三 bution along the Y −
more » ... ection at ( xo , y, 2 。) is given by Equations ( 1 ) and ( 3 ) , Here , B 茘 is regarded as representing the directivity power spectrum along the Y − direction at ( xo , @, xo ) . The directivity power spectro correspond to those of the traversing microphone spectra scopys ) 、 Following th6 Wiener . Khintchiness theorem with respect to the spatial correlation2 , , it is expected that the correlation coe 伍 cient a 工 ong the Y − direction at ( xo , y ,20 ) is given by Equation ( 5) where B 茘 has been nor 皿 alized ・ . Here , assuming that B 茘 has an equally probable continuous distribution as shown by Equation ( 6), tlle Cook ' s formula1 , is der量ved , But the equation ( 5 ) is not practical for a finite rectangular τoom ,量 n particular , at lower frequencies , because,三 n genera1 , we cannot expect the stationarity with respe ¢ t to space . TherefQre, the corre ! atio 耳 ooef 丘cient between A ( xe , } ア A , zo ) and B ( xo , YA 十 」 Ψ, 堵 o ) is given by Equation ( 9)where B 跣 represent the dire ( 沈ivity power spectra as stated above . The reverberant room in our laboratory is τec . tangular as shown in Fig.1. A block diagram for the measurements is shown in Fig.2. At 125 Hz ( 1 / 30ct , ) and 250 Hz ( 1 / 30ct ) , the theoretical results are compared with the experimental ones , as shown in Figs.3 − 12. But the 皿 easurements of the directivity power spectra are n 。 t performed here. It seems that the condition of the sound source posit ... on is reflected those results , and these τesults correspond to the theoretical ones for the mQst part。 Some practical exa 皿 ples that we can assu 皿 e theore − tically the correlation coef 五cients of sound pressure in a rectangular reverberant room , are shown here.
doi:10.20697/jasj.33.11_620 fatcat:ze5qnwcpyrg6jn3qwhorosta24