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PERPENDICULAR DISTANCE FROM THE BAFFLE AXIS IN INCHES 



VARIATION OF SOUND PRESSURE BEHIND 14" & 18" CIRCULAR AND RECTANGULAR 

 BAFFLES WITH PERPENDICULAR DISTANCE OFF THE BAFFLE AXIS 



THE SMOOTH LINE ABOVE EACH PATTERN GIVES THE SOUND PRESSURE WITHOUT THE BAFFLE. 



THE VERTICAL DOTTED LINES GIVE THE THEORETICAL POSITION OF THE "EDGES OF THE BRIGHT 

 SPOT"i.e.. OF THE PRESSURE MINIMA ON EITHER SIDE OF THE CENTRAL PRESSURE MAXIMUM. 



THE CROSS GIVES THE THEORETICAL VALUE 



r AXIS 



THE DISTANCE BEHIND THE BAFFLE AT WHICH THE PRESSURE IS MEASURED IS X; f 'S THE 

 FREQUENCY IN KC. 



Figure 4B. Experimental variation of pressure behind battles. 



