- Title
- Control of resonant acoustic sound fields by electrical shunting of a loudspeaker
- Creator
- Fleming, Andrew J.; Niederberger, Dominik; Moheimani, S. O. Reza; Morari, Manfred
- Relation
- IEEE Transactions on Control Systems Technology Vol. 15, p. 689-703
- Publisher Link
- http://dx.doi.org/10.1109/TCST.2006.890276
- Publisher
- Institute of Electrical and Electronics Engineers (IEEE)
- Resource Type
- journal article
- Date
- 2007
- Description
- Low-frequency reverberant sound fields are usually suppressed by means of either adaptive feedforward control or Helmholtz resonator. Feedforward systems utilize a noise reference signal, error microphone, and loudspeaker to cancel sound propagating in one direction. Due to the requirement for multiple transducers and a powerful digital signal processor, feedforward systems are the most complex and expensive option for acoustic noise reduction. Helmholtz resonators, comprising auxiliary coupled acoustic chambers, are a popular passive technique for the control of dominant acoustic modes. Although lightly damped acoustic modes can be heavily attenuated, the resonators are difficult to tune and require unpractically large cavity volumes at frequencies below 200 Hz. This paper introduces a new technique for the control of low-frequency reverberant sound fields. By connecting an electrical impedance to the terminals of an acoustic loudspeaker, the mechanical dynamics, and hence, acoustic response can be made to emulate a sealed acoustic resonator. No microphone or velocity measurement is required. In some cases, the required electrical circuit is simply the parallel connection of a capacitor and resistor. With the addition of a single pressure microphone, a technique for online circuit adaptation is proposed. Experimental application to a closed acoustic duct results in 14-dB pressure attenuation of a single acoustic mode. Active impedances can be designed by viewing the system model from a feedback control perspective. The resulting electrical impedances, although not passive, are experimentally shown to attenuate four acoustic modes by up to 10 dB.
- Subject
- acoustic impedance; acoustic noise; loudspeakers; optimal control; passive circuits; shunt damping
- Identifier
- http://hdl.handle.net/1959.13/29641
- Identifier
- uon:2597
- Identifier
- ISSN:1558-0865
- Rights
- Copyright © 2007 IEEE. Reprinted from IEEE Transactions on Control Systems Technology, 689-703. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of the University of Newcastle's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to pubs-permissions@ieee.org. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.
- Language
- eng
- Full Text
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