Research On Three-dimensional Space Active Noise Control Approach

Noise pollution is an environmental problem all over the world, which has been paid much attention to. Being exposed to too much noise is harmful to people in physiology and psychology. So reducing noise is an urgent problem that must be solved. The active noise control technology is a hot spot in recent years. Traditional passive noise control technology has many disadvantages, such as too large, too heavy, high cost, etc. The active noise control technology can overcome these problems. It has already shown great commercial value for its excellent control effect on the low-frequency noise.A technique of active control harmonic noise in local space is put forward in this paper. Based on the fact that the sound pressure value of grid nodes represents the sound pressure level of small spaces, the local space is meshed into many small spaces. The quadratic sum of sound pressure of all nodes is used as an error criterion. Then, the secondary sound strength is obtained in the case that the error criterion is a minimum. Finally, the simulation for the active noise control system is performed based on this method. The simulation results show that the system can get large noise reduction, which verifies the effectiveness of this method.A method of control harmonic noise in the whole sound fields is proposed in this thesis. The active noise control system based on this method can control the whole space. But the control ability will weaken for local space.This paper introduces the design of active noise feed-forward control system. Adaptive FX-LMS algorithm is used in this system. Then the single channel system is simulated by using software MATLAB. The simulation results indicate that the system has a good control effect for harmonic noise and broadband noise. Besides, the frequency domain LMS algorithm is deduced, which has important significance for accelerating the computing speed.Finally, the active noise control experiment for local space has been carried out. It confirms the feasibility of active control harmonic noise in local space.