Research On The Algorithms Of Adaptive Anti-noise Speakers

Background noise can destroy the intrinsic acoustical characteristic and model parameter of sound signals, so that deteriorates the communication quality of sound. The adaptive anti-noise speakers can improve effectively communication quality in the strong background noise and is widely applied to industries with high environmental noise. With the rapid progress of techniques on Digital Signal Processor, the price of chip falls, which makes it very useful to research on new fashioned anti-noise speakers based on new hardware and new algorithms.The anti-noise speakers, which is completed by following the ordinary speakers with a digital filter, can enhance speech signals and restrain noise. In this paper the characteristics of sound signals is introduced. The primary principles of adaptive filter techniques and the configuration of adaptive noise-canceling system are also researched. At the same time the performance of adaptive noise-canceling system is analyzed. In this paper the algorithms of adaptive filter are studied by simulation. The standard Least Mean Square algorithm (for short LMS algorithm) possesses evident advantages that it is a simple algorithm easy to realize and the misalignment rate of the output is almost zero when the relativity of input signals is zero. But when the order of the filter is bigger and the relativity of the input signals is strong, there appear its disadvantages, such as slow speed of convergence and large amount of calculation and misalignment. The variable step size parallel LMS algorithm has a higher convergence speed and less misalignment than those of standard LMS algorithm. It is very applicable to realization of DSP as well as processing of voice signals. The MATLAB simulation certifies the advantages of the algorithm.The variable step size parallel LMS algorithm combines with advanced DSP, A/D and D/A chips in the design of adaptive anti-noise speakers, which guarantees the advance of technology of the anti-noise speakers in the aspects of the algorithms andrepresents the mainstreams of anti-noise speaker at present.