双层有源降噪耳罩研究

发布时间：2018-12-14 09:07

【摘要】：针对双层有源降噪耳罩研究。采用实验测量的方法对有源耳罩降噪性能进行研究,提出了新的高性能降噪耳罩,建立了理论模型并进行了实验。研究了耳罩被动降噪所引起的时延,重点研究了存在漏声的情况。首先,总结目前已有的耳罩降噪性能测量方法。发现目前已有测量方法主要针对无源降噪耳罩,在已有测量方法的基础上,提出了有源降噪耳罩的测量方法。利用新提出的测量方法研究了有源耳罩降噪性能。选取了3款降噪耳罩进行测量,对有源降噪耳罩在噪声不同角度入射下降噪性能、多次佩戴情况下降噪性能、大声压级情况下降噪性能和安静情况下本底噪声进行了分析和研究。其次,通过研究骨导传声阈值,讨论了护耳器可以达到的降噪性能极限。为了提高耳罩降噪性能,在原有耳罩基础上做出了改进,使用双层壳体双层耳罩垫的结构,并安装了前馈自适应有源降噪系统,提升了耳罩降噪性能。测量了最新双层结构有源降噪耳罩的降噪性能并与耳罩降噪性能极限相比较,改进过的耳罩降噪性能良好,在某些频段已经逼近甚至超过了降噪性能的极限。最后研究了耳罩的时延问题。首先讨论了耳罩完全闭合的情况,然后重点讨论了存在漏声的情况,针对这种情况提出了全新的模型。传统不存在漏声的耳罩模型中声音只能通过耳罩壳辐射进入耳道,而在存在漏声的耳罩模型中声音还可通过漏声通道辐射进入耳道,因此通过引入微型圆柱形管道来模拟漏声通道并对存在漏声情况的耳罩建模。实验中在耳罩垫与人工头接触部分插入一个圆柱形微型管道用来模拟漏声通道并进行测量,实验测量值与理论模型预测值吻合较好,验证了模型的正确性。
[Abstract]:Research on double layer active noise reducing earmuffs. The noise reduction performance of active earmuffs is studied by means of experimental measurement. A new high performance noise reducing earmuffs is proposed. The theoretical model is established and the experiments are carried out. The delay caused by passive noise reduction in earmuffs is studied. Firstly, the existing methods for noise reduction of earmuffs are summarized. It is found that the existing measurement methods are mainly aimed at passive noise reduction earmuffs. Based on the existing measurement methods, the measurement method of active noise reduction earmuffs is proposed. The noise reduction performance of active earmuffs is studied by using the new measurement method. Three types of noise reduction earmuffs are selected to measure the noise reduction performance of active noise reduction earmuffs under different angles of noise, and the noise reduction performance of active noise reduction earmuffs under multiple wear conditions. The performance of noise reduction at high sound pressure level and background noise under quiet condition are analyzed and studied. Secondly, the noise reduction performance limit of ear protector is discussed by studying the threshold of bone conduction. In order to improve the noise reduction performance of the earmuffs, an improvement was made on the basis of the original earmuffs. The structure of the double-shell double-layer earmuffs was used, and the feedforward adaptive active noise reduction system was installed to improve the noise reduction performance of the earmuffs. The noise reduction performance of the new dual-layer active noise reduction earmuffs is measured and compared with the limit of the noise reduction performance of the earmuffs. The improved earmuffs have good noise reduction performance and have approached or even exceeded the noise reduction performance limits in some frequency bands. Finally, the delay problem of earmuffs is studied. Firstly, the complete closure of the earmuffs is discussed, and then the problem of sound leakage is discussed, and a new model is proposed. In the traditional ear muzzle model without leakage, the sound can only enter the ear canal through the ear shell radiation, while in the ear cover model, the sound can also be radiated into the ear canal through the leakage channel. Therefore, a miniature cylindrical tube is introduced to simulate the acoustic leakage channel and to model the earmuffs with sound leakage. In the experiment, a cylindrical miniature pipe was inserted into the head-head of the earmuffs to simulate and measure the acoustic leakage channel. The experimental results are in good agreement with the predicted values of the theoretical model, which verifies the correctness of the model.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB535

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