抄録
A sound-energy flux-meter applicable for accurate measurements is discussed. Its microphone head consists of two pressure microphones of nearly same characteristics; the voltage e_v proportional to the particle velocity v is obtained by time integration of the difference in voltage of the two microphone outputs. As the sound-energy flux density P is defined by the time average of p×v, the sound energy flux-meter must necessarily contain a multiplier such as the electronic wattmeter. The authors used a phase sensitive detector of new type as the multiplier, to construct a instrument with the accuracy of 2-3 %.
