The present invention is a method of estimating formation properties by analyzing acoustic waves that are emitted from and received by a bottom hole assembly. A bottom hole assembly may be deployed in a borehole to estimate formation properties. From the bottom hole assembly, a source signal may be emitted and at least one signal may be received by one or more receivers in the bottom hole assembly. Analysis of the frequency dependent characteristics of the received signal allows the estimation of the formation properties of interest, including pore pressure. The formation properties of interest may be used to monitor a wellbore pressure safety margin and to optimize drilling and weight.