WSEAS Transactions on Circuits and Systems
Print ISSN: 1109-2734, E-ISSN: 2224-266X
Volume 17, 2018
On The Achievable Amplification of the Low Order NLMS Based Adaptive Feedback Canceller for Public Address System
Authors: Ryan D. Reas, Roxcella T. Reas, Joseph Karl G. Salva
Abstract: In an environment wherein public address system are used to address the general public, acoustic feedback occurs unpredictably which significantly degrades the acoustic quality of the information signal. A low order adaptive filter is then presented, with the objective that is to reduce the effect of acoustic feedback of the public address system that might occur at any point within the area. The system covers a multi-tapped finite impulse response (FIR) low order adaptive filter that is implemented in field programmable gate array (FPGA). The effects of the adaptation constant adaptation constant and filter length was investigated. During the evaluation, the acoustic activity of the environment was observed by a spectrum analyzer and spectrograph. Results show that with large adaptation constant, the adaptive filter was able to quickly reduced before the system exhibit an unstable behavior. However, results also show that the magnitude of the output information signal of the public address system with large adaptation constant is lesser compared to a smaller adaptation constant of the adaptive filter. This shows that the adaptation constant greatly affects how the adaptive feedback canceller eliminate the acoustic feedback but also reduces the amplification of the public address system.
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Pages: 114-128
WSEAS Transactions on Circuits and Systems, ISSN / E-ISSN: 1109-2734 / 2224-266X, Volume 17, 2018, Art. #15