158 



ASSOCIATED EQUIPMENT: DOMES AND BAFFLES 



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X-1INCH 

 + .20 KC 



PERPENDICULAR DISTANCE FROM THE BAFFLE AXIS IN INCHES 



VARIATION OF SOUND PRESSURE BEHIND 18" CIRCULAR BAFFLE 

 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 p 



r AXIS' 

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

 FREQUENCY IN KC. 



Figure 4A. Experimental variation of pressure behind baffles. 



