DEVELOPMENT OF NOISE REDUCTION METHOD FOR GRAIN DRYERS

记录了单元式烘干机周围43个点和农村电梯内23个点的噪声。在实验室测试中，我们用FFT分析仪对测点使用反声前后的声频进行了分析。用傅立叶变换对扬声器噪声源和反向噪声源的0、45、90、135、180度夹角和距离分别为1.5m和3.0m的7个样本进行了测量和分析，结果表明，反向噪声的产生使扬声器的噪声水平降低了约10(DB)到20(D B)。排风风道中扬声器的反向噪声实际上使排气噪声降低了约2分贝。用反向噪声来模拟噪声抵消，并利用记录的噪声源获得了与前述实验结果相似的降噪特性。模拟结果也为噪声控制提供了一些有效的方法。

The noize of 43 points around a unit dryer and 23 points in a country elevator were recorded.In the laboratory tests we used FFT analyzer to analyze the frequence of sound before and after using reverse sound for the measuring points. we took seven samples, the 0,45,90,135 and 180 degrees of angle and the distance of 1,5m and 3.0m around the noise source and the reversed noise source of the speaker were measured and analyzed by the FFT.The results indicated from about 10 (dB) to 20 (dB) reduction of noize level by the reversed noise generation. The reversed noise by a speaker in the exhaust duct for dryng air actually reduced the exhaust noise by about 2 dB.The similation of noize cancelation by reversed noise were developed, and using the recorded measured noise source the noise reduction characteristics similar to the preseding experimental results were obtained. The simulation was also suggestive of some effective method of noise control.