P Pressure. 



p Acoustic pressure (anomaly from hydrostatic value 



of P). 



Q Quality factor (see page 11 ). 



r Resistive (real) part of boundary impedance Z; also 



bubble radius (page 90 only). 



S Bounding surface. 



s Particle displacement vector (components s^). 



T Absolute temperature (T mean value, T anomaly 



from mean value); also surface tension (page 90 only). 



t Time 



t Reverberation time for cavity with pure water. 



^total Reverberation time for cavity with sample sea water. 



v Fluid velocity vector (components v^). 



v Magnitude of velocity vector (v 2 = v 2 + v 3 3 + u 3 2 ). 



V Volume. 



x^ Components in a Cartesian coordinate system (i = 1, 2, 3). 



Z Boundary impedance (Z^ and Z' ■ , 1 = 1, 2, 3 correspond 



to values pertinent to the six faces of a rectangular 

 cavity resonator). 



a ^ Spatial (or range) coefficients of attenuation (db/kyd). 



ci£ Temporal coefficient of attenuation (db/sec); see 



page 57 for special designation. 



(3 Parameter controlling viscous loss, (2\a +\ i )A . 



Y Transmission coefficient for energy flux. 

 AL Effective tkickness of walls (w/p ). 



b^ft Unit diagonal tensor; unity for i =h, zero for I ^h. 



r\ Anomaly of specific entropy from equilibrium value 



(ergs/gm °K). 



® Dilation, V • g. 



k Thermal diffusivity. 



