Measurement of the mutual radiation impedance of loudspeakers from electrical input power and diaphragm velocities

Abstract

In a previous paper [Suzuki et al., J. Acoust. Soc. Am. Suppl. 1 86, S21 (1989)], a technique to obtain self and mutual radiation impedances from the measurement of radiated power and diaphragm velocities was reported. However, the measurement of acoustical power is time-consuming and less accurate compared to the measurement of electrical parameters. A method presented here is to obtain the mutual radiation impedance from the measurement of electrical input power and diaphragm velocities. This technique allows a better understanding of how the input electrical power is distributed in the loudspeaker and the effect of the mutual interaction. A difficulty of this technique is that the electrical power consumed by the voicecoil resistance is much larger than the mechanical and acoustical powers. Another disadvantage is that the self-radiation resistance cannot be measured separately from the mechanical resistance. A result of the mutual radiation resistances obtained from the previous and present techniques is compared.