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Proceedings Paper

Acoustic panels using magnetostrictive Metglas
Author(s): Michael J. Gerver; James H. Goldie; Scott Makseyn; John Oleksy; John J. Doherty; Paul Remington
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Paper Abstract

Passive barriers to transmission of sound waves at frequencies below 500 Hz require large masses. Active noise cancellation systems, on the other hand, are complicated and expensive. We are developing a method for noise control, using an array of panels of magnetostrictive Metglas, which combines the low mass and flexibility of active noise control with the relatively low cost and simplicity of passive noise control. The method is based on the well known fact that an acoustic panel with a reaction mass, resonant at the frequency of the sound wave, will completely reflect that wave, simulating an infinite mass. By wrapping a coil around each Metglas panel, and terminating the coil in an impedance, the stiffness of the Metglas, and hence the resonant frequency of the panel, can be controlled by varying the terminal impedance. By choosing a terminal impedance which is itself frequency dependent, the panel can be made to resonate, and hence to have effective infinite mass, at all frequencies (over some fairly large range) simultaneously. This generally requires negative impedance, which can be produced by a simple circuit with an amplifier and feedback loop. In effect, the Metglas acts like both microphone and speaker in an active noise control system. Preliminary experimental results will be presented.

Paper Details

Date Published: 9 June 1999
PDF: 14 pages
Proc. SPIE 3668, Smart Structures and Materials 1999: Smart Structures and Integrated Systems, (9 June 1999); doi: 10.1117/12.350701
Show Author Affiliations
Michael J. Gerver, Independent Consultant (United States)
James H. Goldie, SatCon Technology Corp. (United States)
Scott Makseyn, SatCon Technology Corp. (United States)
John Oleksy, SatCon Technology Corp. (United States)
John J. Doherty, BBN Technologies (United States)
Paul Remington, BBN Technologies (United States)

Published in SPIE Proceedings Vol. 3668:
Smart Structures and Materials 1999: Smart Structures and Integrated Systems
Norman M. Wereley, Editor(s)

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