The Active Minimization of Harmonic Enclosed Sound Fields
The total time averaged acoustic potential energy in a steady harmonic sound field can be expressed as a positive definite quadratic function of the complex strengths of a number of “secondary sources” of sound introduced into the enclosure. For a given number and location of secondary sources, there is a unique set of complex source strengths which minimises this potential energy. This analysis is applied to the case of a lightly damped enclosure excited by a point primary source at a frequency well above the Schroeder large room frequency. It is demonstrated that in this case, the maximum reduction that can be achieved in the potential energy of the sound field is critically dependent on the relative locations of primary and secondary sources.
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