| Paper: | AE-P5.12 | ||
| Session: | Acoustic Echo Cancellation and Active Noise Control | ||
| Time: | Friday, May 19, 10:00 - 12:00 | ||
| Presentation: | Poster | ||
| Topic: | Audio and Electroacoustics: Active Noise Control | ||
| Title: | Optimal Loop-Shaping in the Cepstral Domain for Active Noise Canceling Headsets | ||
| Authors: | Jean Laroche, Creative Advanced Technology Center, United States | ||
| Abstract: | Simple active noise-canceling systems (such as noise canceling headphones) use a feedback mechanism whereby the signal recorded by microphone placed near the loudspeaker is phase-inverted and sent back through the loudspeaker via a feedback filter. Such systems can be implemented using analog circuitry, are fairly inexpensive, and achieve reasonably good performance at low frequencies (below 500Hz). The feedback filter is designed to achieve a high gain at low-frequencies (for best noise reduction) while maintaining closed-loop stability under various conditions. To design the feedback filter, fairly ad-hoc techniques were traditionally used under the broad denomination of "loop-shaping" until the advent in the 80's of optimal H_infinity algorithms. The design technique outlined in this paper shares the intuitive approach of traditional loop-shaping methods, but removes most of the guess-work while producing optimal filters that guarantee closed-loop stability. The main idea is to represent the filter in the cepstral domain, where gain and phase constraints take a convenient linear form, and use linear programming to design the optimal feedback filter | ||
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