Study on the Acoustic Transformer by Means of Motional Impedance

Abstract

A confined elastic medium bounded by two surfaces which are able to displace independently is called an acoustic transformer. The theory of the acoustic transformer and a moving coil type telephone receiver are described. Experiments were worked out on an aco stc transformer loaded by an orifice, and coupl d with a moving coil type telephone receiver were measured by changing the volume of the acoustic transformer and the lead. By determination of the constants of the acoustic transformer at every case by analysis of the total mechanical impedance of the vibrating system obtained by measurements of the motional impedances, the theory of the acoustic transformer was confirmed to be applicab'e to any load conditions. In this paper, the theory and experimental results are described in detail.