This is a simple kit that models the way that earthquakes can be located. It consists of two microphones on long leads, an adaptor and an extension lead. The two microphones are placed at a distance apart, and connected to the microphone input of a computer running sound recording software (stereo channels).
Clapping nearer one of the microphones demonstrates that there is a difference in the arrival times at each of the microphones.
This kit can also be used to estimate the speed of sound.