I want to be able to differentiate between longitudinal(P) and Shear(S) waves in solids. Using one Acoustic emission (AE) senor placed 2 to 20 cm form a AE source e.g. a stress induced crack or pencil lead test, how can one detect both the P and S waves and determine what part of the recieve waveform corresponds to which wave. I know that the P wave travels typically at twice the velocity of the S wave and also that the S wave has lower frequency (at least this is true in seismology). My hypothesis is to use analysis of the frequency and maybe with a time-frequency graph I may be able to detect when each wave mode occurs. Maybe a filter or wavelet analysis could also be helpful. My question is basically: Do the two waves occur at different frequencies and if so what sort of difference? Is it pratical to use some sort of frequency based technique to determine when each wave has arrived at a particular sensor? Does a crack from stress being applied to a material e.g metal produce a destinct P and S wave at different frequencies or are they blended into each other somehow?