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 ͑SCL͒ configuration and a double-composite-leaf ͑DCL͒ 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 frequencies͒, 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.

An experimental investigation of two active segmented partition arrays

“…13 Electronic crosstalk was consistent with that discussed in Ref. 17. Neither of these concerns posed a limitation for most transmission loss measurements.…”

“…A recent experimental study 17 validated the modeling and theoretical predictions for two individual modules from Ref. 16: configuration 2 ͑a SCL arrangement͒ and configuration 3 ͑a DCL arrangement͒.…”

“…17, several of their functions were duplicated because of the increased number of controlled channels. A Hewlett-Packard 3566A PC Spectrum/ Network analyzer was expanded to 16 channels.…”

“…27 swept sine wave stimulus used to drive the source loudspeaker. 17 As suggested in Fig. 4, four additional microphones were used to probe acoustic pressures within the cavities of the DCL ASP array.…”

“…[1][2][3][4][5][6][7][8][9] The authors of this paper have explored them with the general aim of controlling sound transmission through lightweight structures via efficient, global control of transmitting surface vibrations. [10][11][12][13][14][15][16][17] One recent investigation 16 explored background and basic concepts of ASP design and use, focusing on modeling, theoretical analysis, and numerical transmission loss predictions for four individual module configurations. Two modules involved single-composite-leaf ͑SCL͒ configurations and two involved double-composite-leaf ͑DCL͒ configurations.…”