Research Of Adaptive Echo Cancellation Algorithm Applied To Public Address

Public Address, including background broadcast emergency broadcast and campus broadcast,etc. Background broadcast is mainly used to create a good atmosphere of the environment.Emergency broadcast is when an emergency occurs, the background broadcast forciblyswitched to emergency broadcast, using it to command and evacuate people. Campusbroadcast is mainly used in the classroom and dormitory broadcast the notification, Englishlistening test, campus background music, and playing on the playground broadcast thegymnastics, etc. Therefore, public address can be as simple as a controllable audioamplification system. It has the common characteristics of the loudspeaker system: containamplifiers, microphones and speakers. But in today’s various kinds of sound amplificationsystem, as long as there have a microphone and speakers at the same time, will inevitablyappear echo feedback phenomenon. Serious echo feedback not only affects the normal voiceinformation transmission, but also can appear the howling (Also called howlback); even thewhole sound amplification system cannot work normally, and even damage the speakers andamplifiers, etc. If it occurs when emergency broadcast command people evacuated, whichbelong to serious accidents. Therefore, echo cancellation in public radio loudspeaker systemis an indispensable link.Howling cancellation main function is to eliminate the coupling between speakers andmicrophone echo, undermine its positive feedback loop that can guarantee the stability of thepublic address system. The traditional howling cancellation method can improve theenvironment of room acoustics, use equalizer or frequency shift in the amplification system,etc. But these methods not only need professional personnel to adjust, but also hard tooperation, and these methods for sound quality damage are bigger.With the rapid development of digital signal processing technology, the use of digital signalprocessing for filter has been very mature, this paper introduces the public broadcastingsystem used in the hardware platform, and then study a variety of different algorithms todetect and suppress interference of the howling, and through MATLAB software to simulationand real test, comparing various algorithms, make its can be applied in the publicbroadcasting system all sorts of different hardware platforms, to prepare for the futuredevelopment of related products. Finally, the paper chose the MCU+fixed-point DSPplatform, the previous analysis of the algorithm was tested and verified the detectionalgorithm and adaptive filtering algorithm can be realized.