For the case of longitudinal quadrupoles having their axes in the z,-direction and 
being transported in the 2,-direction at Mach number M, the mean-square sound pressure is 
given by 
a 1 1 Sense 
pe = \\ ‘Titi yh Mam Me 
16 72c* 72(1-M cos 6)4 
2 
92 |3(1-M?) cos*@ 12M(1-M”) cos* 6 ps 
aay ——E_ (a) eoseioOlieostarl Ta ie 
r (1-M cos 6) 1-M cos @ 
4 4 3 2 
©’ | 9(1-M2) cos*@ 36M(1-M2) cos?6 6(1-9M7) (1-M?) cos? 6 
P|) ee Se eee 
ro (1-M cos 6)* (1-M cos 6)3 (1-M cos 6)? 
12(1-3M?) (1-M?) M cos 6 3 = 
+ (1-3M Tina (aniann 92 
1-Mcosé 33/538 ee ee 
It may be seen that introducing a convection velocity somewhat complicates the ex- 
pressions for the general sound field. The intensity could be obtained for the case of convec- 
tion of dipoles and quadrupoles, but the complexity would be great indeed. 
32 
