An Empirical Expression of Elastic Sound Speed of Materials at High Pressures

After treating analyticaly the measured elastic sound speed c of seven materials, including aluminum, iron, copper and so on, at high pressures, it is shown that the change of the elastic sound speed with pressures may be described as ln c=A0+A1ln p+A2ln2p , here, A0, A1, A2, are meterial constants, p is the pressure. The relative error between the fitting data and the measured data is less than 5%.