發(fā)布時間：2018-12-14 09:07

【摘要】：針對雙層有源降噪耳罩研究。采用實(shí)驗(yàn)測量的方法對有源耳罩降噪性能進(jìn)行研究,提出了新的高性能降噪耳罩,建立了理論模型并進(jìn)行了實(shí)驗(yàn)。研究了耳罩被動降噪所引起的時延,重點(diǎn)研究了存在漏聲的情況。首先,總結(jié)目前已有的耳罩降噪性能測量方法。發(fā)現(xiàn)目前已有測量方法主要針對無源降噪耳罩,在已有測量方法的基礎(chǔ)上,提出了有源降噪耳罩的測量方法。利用新提出的測量方法研究了有源耳罩降噪性能。選取了3款降噪耳罩進(jìn)行測量,對有源降噪耳罩在噪聲不同角度入射下降噪性能、多次佩戴情況下降噪性能、大聲壓級情況下降噪性能和安靜情況下本底噪聲進(jìn)行了分析和研究。其次,通過研究骨導(dǎo)傳聲閾值,討論了護(hù)耳器可以達(dá)到的降噪性能極限。為了提高耳罩降噪性能,在原有耳罩基礎(chǔ)上做出了改進(jìn),使用雙層殼體雙層耳罩墊的結(jié)構(gòu),并安裝了前饋?zhàn)赃m應(yīng)有源降噪系統(tǒng),提升了耳罩降噪性能。測量了最新雙層結(jié)構(gòu)有源降噪耳罩的降噪性能并與耳罩降噪性能極限相比較,改進(jìn)過的耳罩降噪性能良好,在某些頻段已經(jīng)逼近甚至超過了降噪性能的極限。最后研究了耳罩的時延問題。首先討論了耳罩完全閉合的情況,然后重點(diǎn)討論了存在漏聲的情況,針對這種情況提出了全新的模型。傳統(tǒng)不存在漏聲的耳罩模型中聲音只能通過耳罩殼輻射進(jìn)入耳道,而在存在漏聲的耳罩模型中聲音還可通過漏聲通道輻射進(jìn)入耳道,因此通過引入微型圓柱形管道來模擬漏聲通道并對存在漏聲情況的耳罩建模。實(shí)驗(yàn)中在耳罩墊與人工頭接觸部分插入一個圓柱形微型管道用來模擬漏聲通道并進(jìn)行測量,實(shí)驗(yàn)測量值與理論模型預(yù)測值吻合較好,驗(yàn)證了模型的正確性。
[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.
【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TB535

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本文編號：2378351