82 



ACOUSTICAL ELEMENTS 



.02 .04 .08.1 .2 



e 10 20 



2TrR 



Fig. 5.1. The resistive r, and reactive .v, components of the air load per unit area of the 

 following radiators: 1. piston of radias R set in an infinite baffle; 2. a pulsating sphere of 

 radius R\ 3. an oscillating sphere of radius R. Note: the ordinate scale of the charac- 

 teristics labeled 3 must be multiplied by one-third. See Sec. 5.9. 



where R = radius of the sphere, in centimeters, 



p = density, in grams per cubic centimeter, 

 k = I-kIX 



X = wavelength, in centimeters, and 

 c = velocity of sound, in centimeters per second. 

 The acoustic impedance of the air load upon a pulsating sphere is 



PC / (kRy+j(kR) \ 

 ^^ ^TrR\ 1 + {kRf ) 



5.15 



