Research And Implementation Of Acoustic Feedback Suppression System Based On DSP

Acoustic feedback is a very common phenomenon in modern acousticamplification system. The large hall, multimedia classrooms, vocal concerts all needto be equipped with different kind of acoustic amplification system. And with thedevelopment of embedded applications, portable electric equipments, hearing AIDS,and other products make the amplification system more and more widely used. In theamplification system, when the microphone and speaker in the same sound field, partof the signal components by the voice of the speaker will be feedback to themicrophone. Such feedback acoustic signal will be repeatedly collected and amplified.Slight sound feedback can lead to a distortion and affect the sound effects in practicalapplication. Heavy acoustical feedback will lead to the speaker screeched "mega",make amplification system not only lose their role, and also affect the normalactivities. For a long time, acoustic feedback inhibition is a problem to be reckonedwith in the acoustic applications. With the development of modern digital signalprocessing field, acoustic feedback inhibition technology start from passive inhibitiongradually into active inhibition, acoustic feedback inhibition treatment to improve thespeed and the effect of a certain. At the same time, the acoustic feedback suppressionstill has many problems needed to be resolved. So, the acoustic feedback inhibitionhas great research value and market value.This article based on the commonly used sound feedback inhibition solutions andthe feedback signal characteristics, and do further researches of automatic acousticfeedback inhibition function and structure of the system. First of all, constructed anacoustic feedback platform and add random parameters on the basis of imagemodeling method using the MATLAB environment. Avoiding the testing workdependence on the actual circumstances, simplifies the test steps, and greatly reducesthe cost of development. The Second job was to complete the analysis of the acousticfeedback suppression system overall structure. The function of the whole system willbe divided into sound feedback decision module and feedback processing module.Then this paper introduced details in the sound feedback judgment and feedbackprocessing module algorithm implementation. Acoustic feedback judgment function isfocused on determining acoustic feedback and implement high positioning accuracy,this per used enhanced FFT solution to judge by threshold whether the acousticfeedback happened. Furthermore, we need to achieve higher frequency accuracy. This paper analyses several kind of high frequency spectrum refinement algorithms and tryto find the most appropriate algorithm for our system. Finally our system can achieve0.5Hz@1KHZ frequency localization accuracy, which was very unbelievable. Inthe acoustic feedback processing module, through a variety of scheme comparisonand analysis, finally adopts the LMS adaptive trap to optimize the algorithm of thewhole system. At the last, this paper completed the acoustic feedback cancellationsystem hardware implementation by analyzing TMS320C6713DSP hardware module.And based on the hardware module, I design the software framework of the wholeDSP system and complete functions and made the process simplified. Finally thispaper completed the research and implementation of DSP acoustic feedbacksuppression system.