The method of determination of coefficient of attenuation of amplitude and phase of energy of acoustic waves in an inhomogeneous half-space is considered. The method is based on energy model of the processes of excitation, transmission, reflection and reception of acoustic pulse taking into account the laws of conservation (balance), change, transport and packaging of energy. This model has defined the physical meaning of attenuation, as the time shift between the left in the past and transmitted into the future energy by the physical system, the information about the lost energy is transferred into the future as unlike of accepted energy from a given energy which are controlled on the surface of the half-space.