Construction of an Analogue Correlator for Acoustical Measurements

It is only in recent years that the process of correlation has been applied to acoustical measurements. The correlator used may be either a digital or an analogue machine, each having its own advantages. The machine to be described is an analogue correlator which is suitable for most acoustical measurements, especially those involving long time delays. The main part of the correlator is a standard studio tape recorder which can be used for general recording purposes when not required for correlation.