许多工业和军事噪声是冲击噪声和持续性稳态噪声兼而有之的“混合噪声”，混合噪声的总烦恼度与危害明显高于单一噪声，因此混合噪声的有源控制研究具有重要的现实需求，是有源噪声控制中无法回避的问题。本申请针对冲击噪声和持续性稳态噪声兼有的混合噪声的有源控制，重点研究三个关键问题：(1)设计有源控制的自适应算法，该算法在稳定性、收敛速度与降噪量指标上要优于现有算法直接用于混合噪声的结果。同时给出该算法的步长界限、收敛速度、收敛后误差等的理论分析。(2)研究适于混合噪声的有源控制前反馈组合结构，该结构能减轻前反馈结构间的相互影响，使得两者能够独立工作并保持稳定，理论上分析出该结构在混合噪声条件下的稳定性条件及可达到的降噪量。(3)检验混合噪声有源控制实际应用的可行性,在自由声场和实际混合噪声环境进行有源控制实验，获取降噪量、降噪带宽、系统稳定性的结果。

The mixed noises which are combined by impulse and continuous steady state noise (called mixed noise for short) do exist widely in the industrial and military environments, the annoyance and harm of mixed noise is much severer than the noises with relatively single characteristics, therefore active control of mixed noise has important realistic demand, and is an inevitable issue for the engineering application of active noise control. Much attention is paid and great progress has been made on the active control of the continuous steady noise and the impulse noise. However, little work is presented to address the problem about active control of mixed noises. This project aims to find the appropriate methods and technologies for active control of mixed noises and focuses on three critical problems: (1) design the efficient adaptive algorithms for active control of mixed noise. The stability, convergence speed and the steady state performance of the designed algorithms should outperform the existing algorithms, the theoretical analysis of the step-size boundary, convergence speed and steady state error should also be derived; (2) study the suitable hybrid feedforward and feedback structures active control of mixed noise, which should alleviate the influence between the feedforward and feedback structures, guarantee the stability of the whole structure. The stability conditions and noise reduction performance of the hybrid structure should be analyzed theoretically; (3) validate the feasibility of active mixed noise control in free field and real mixed noise environments, obtain the results including noise reduction, bandwidth and system stability.