@wikipedia
\mbox{v} = \sqrt{\left( \frac{\partial p}{\partial \rho} \right)_S}
It differs for p-wave and s-wave:
\mbox{v}_p = \sqrt{ \frac{K + \frac{4}{3} G}{\rho} }
\mbox{v}_s = \sqrt{ \frac{G}{\rho}}
Physics / Mechanics / Continuum mechanics / Mechanical waves / Body wave / Speed of Sound
[ p-wave ] [ s-wave ]