An experimental investigation of two module configurations for use in active segmented partitions

Abstract

Individual modules intended for active segmented partitions should be carefully analyzed before they are advanced as viable tools for active sound transmission control. In this paper we present experimental evaluations of two vibration-controlled modules: a single-composite-leaf (SCL) configuration and a double-composite-leaf (DCL) configuration. Experimental apparatuses and procedures are introduced to assess their normal-incidence transmission losses over a bandwidth from 40 to 1970 Hz. The average transmission loss of the passive SCL module is found to be 21 dB. If its transmitting diaphragm acceleration is minimized through active control, transmission loss increases somewhat at lower frequencies but decreases at higher frequencies, producing no increase in the average value. The average transmission loss of the passive DCL module is found to be 43 dB. After its transmitting diaphragm acceleration is actively minimized, the transmission loss increases substantially at all frequencies (especially at low frequencies), to produce an average value of 77 dB. Thus, while both configurations have the same underlying control objective, the DCL module yields a 56 dB average improvement over the SCL module through simple configurational changes. An alternative control scheme is investigated that minimizes acoustic pressure in the DCL module cavity, but it is found to be less effective.