松子开闭声学特性的试验研究

利用声学测试系统,对开口松子与未开口松子声学特性进行测试,并根据不同松子大小、不同下落高度分别进行试验,分析松子碰撞后的波形图、频谱图,探讨声学特性与松子开闭状态的关系.通过试验发现,开口与未开口松子的波形图和频谱图有明显区别,开口松子在3500～7000Hz之间有一能量高峰,而未开口松子能量分布比较平均,无明显凸峰.同一类松子,其下落高度、大小不同对主频没有明显影响,其频谱图基本相同.可以利用开口松子与未开口松子的声学特性不同进行松子分类.

Experimental Study on Acoustical Characteristics of Pine Nut with Open and Closed Shells

An acoustical test system was developed to test the characteristics of pine nuts with closed and open shells. The signal of sound wave and frequency spectrum of pine nuts with open and closed shells were obtained under different dimensions and drop heights of pine nuts. According to the test and analysis, it was found that there were distinct differences between pine nuts with open and closed shells on the signal of sound wave and frequency spectrum. There was an energy peak value between 3 500 and 7 000 Hz on the frequency spectrum of an open pine nut. The frequency spectrum of closed pine nut was flatter. There was no big difference on the frequency spectrum under the different dimensions and drop heights for same kind of pine nuts. As the result of test and analysis, the discrimination of characteristics of pine nuts with closed and open shells could be used to sort the open and closed pine nuts.