Hi 
one of the result that report in forcite mechanical properties results is  Velocities of sound. in this reult 9 results were reported: X1, X2,X3,Y1, Y2, Y3 , Z1,Z2 and Z3. whats the meaning of these paramters? i know that the veloxity of sounds in materials is a number but i don't know what is the these 9 parameters
please help me 
best