Hot firings show that the frequency of the oscillating shock is close to the acoustic frequency. 热试结果表明，振荡激波的频率与声频相近。
Using the acoustic noise signal generated by driving motor vehicles to vehicle classification is a new and promising method. 利用车辆行驶过程中所产生的声频噪声信号进行车型分类是一种新方法，有较大应用前景。
Its frequency response has to be flat over the whole audio range. 它的频率响应在整个音频范围内有所下降。
This paper introduces the principle and tested results of measuring nodulizing grade by audio frequency method. 介绍了音频法检测铸件球化级别的原理及试验结果。
