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TitleThe stability of multichannel sound systems with frequency shifting
Publication TypeJournal Article
Year of Publication2004
AuthorsPoletti, M.A.
JournalJournal of the Acoustical Society of America
Pagination853 - 871
Date Published2004
ISSN00014966 (ISSN)
KeywordsAcoustic waves, acoustics, analytic method, article, artifact, calculation, computer simulation, Frequencies, Frequency-shifts, mathematical analysis, Modulation artefacts, Monte Carlo method, Multichannel sound systems, priority journal, Room acoustics, Signal detection, simulator, sound, sound detection, steady state, time, Time varying systems, Time-variation
AbstractTime-varying components are used in some multichannel sound systems designed for the enhancement of room acoustics. Time-variation can usefully reduce the risk of producing ringing tones and improve stability margins, provided that any modulation artefacts are inaudible. Frequency-shifting is one form of time-variation which provides the best case improvement in loop gain, and for which the single channel stability limit has been derived. This paper determines the stability limit for multiple channel systems with frequency-shifting by generalizing the previous single-channel analysis. It is shown that the improvement in stability due to frequency-shifting reduces with the number of channels. Simulations are presented to verify the theory. The stability limits are also compared with those of time-invariant systems, and preliminary subjective assessments are carried out to indicate useable loop gains with frequency-shifting. © 2004 Acoustical Society of America.

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