WSEAS Transactions on Acoustics and Music
Print ISSN: 1109-9577
Volume 5, 2018
A Simulation Based Approach of Characterizing Acoustic Feedback in Public Address System
Authors: , ,
Abstract: Public address system had been in use for a very long time. Since it was first developed, it has evolved from analog public address system to digital public address system. Either analog or digital public address system, its general purpose is to allow efficient communication in a large number of crowd. The object of the public address system is to amplify the received acoustic signal. However, throughout the history of public address system, it had been plagued by problems. One of the problems in public address system is the existence of positive feedback which severely affects the quality output signal. This paper examines the characteristic of acoustic feedback through simulation. The public address system and the acoustic feedback path was based on a low pass finite-impulse-response (FIR) filter. The simulation was performed by increasing slowly the gain of the public address system until the output signal grows exponentially and uncontrollably. The output signal of the public address system with the gain to which it behaves uncontrollably was compared with the output signal of the public address system with a gain 3dB lower. Simulation results show that the acoustic feedback signal has a fixed few narrow frequency components and one of its frequency components dominates the rest of time. Furthermore, it was observed that the public address system with music applied as input acoustic signal and with the existence of acoustic feedback path will have an approximate output signal that is a linear sum of the acoustic feedback signal and music signal. However, the existence acoustic feedback is unpredictable thus its characteristic is hard to quantify. With this, classical way of filtering or signal suppression is inefficient in dealing with the existence of acoustic feedback.
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Pages: 12-19
WSEAS Transactions on Acoustics and Music, P-ISSN: 1109-9577, Volume 5, 2018, Art. #2