双扬声器近场声源重放实验研究

该文针对电子器件散热用的一款变速轴流风扇的气动噪声及其降噪方法进行实验研究。首先利用风扇旋转轴等高平面内圆周分布的传感器阵列测量风扇不同转速下远场噪声分布,总声压级与转速的对数关系验证散热风扇主要气动噪声属于偶极源噪声,频谱分析显示离散单音噪声为主要噪声影响因素。基于管道声学理论的管道模态截止方法,研究进出风口安装圆形短管对风扇气动噪声的影响,实验结果显示不同位置、不同长度的短管对风扇远场噪声影响不同。额定转速下,在进风口安装2 cm管道可以使远场1 m处平均总声压级下降4.1 dB(A),降噪效果显著。模态测量结果显示,此种情况下对应离散单音处的风扇主要模态幅值大大降低,风扇离散单音噪声降低从而噪声总声压级大幅减小。该方法为散热风扇降噪提供了一种新的途径。

Experimental study on near-field sound source reproduction using dual loudspeaker

The researches of louderspeaker spatial sound reproduction system mainly concentrate on the direction perception of the reproduced sound source while neglect the distance perception of the sound source.The near-field head related transfer functions(HRTFs)at different distances are used to adjust the prefilter coefficients,so as to reproduce near-field sound sources at different distances.The direction discrimination at equal distances and the distance discrimination at the same direction of the near field source is studied under several typical dual-loudspeaker configurations.The experimental results show that back-front confusion exists in such near-field sound reproduction,and the direction judgement is relatively more accurate,when the virtual sound source and the loudspeakers locate in the same front or back half-plane.In the area where the directions are accurately judged,the subject can differentiate the distances of the sound sources accurately,and the more the sound source deviates from the median plane,the more accurately the distance perception.This study provides a more comprehensive evaluation of the distance reproduction performance of virtual sound sources with multi-speaker configuration.