The CH method is a downhole method for the determination of material properties of soil and rock. A source capable of generating shear and compressional waves is lowered in one of the boreholes and a pair of three component geophone receivers, coupled each either, are lowered to the same depth in two additional boreholes set at evenly spaced increments (typically 10 and 20 feet from the source borehole) in a line.
The receivers are positioned on the side of the borehole casing to allow detection of the passage of shear and compressional waves, an addition the material damping can be estimated from CH test results.