Hot firings show that the frequency of the oscillating shock is close to the acoustic frequency. 熱試結果表明，振蕩激波的頻率與聲頻相近。
Using the acoustic noise signal generated by driving motor vehicles to vehicle classification is a new and promising method. 利用車輛行駛過程中所產生的聲頻雜訊信號進行車型分類是一種新方法，有較大應用前景。
Its frequency response has to be flat over the whole audio range. 它的頻率響應在整個音頻範圍內有所下降。
This paper introduces the principle and tested results of measuring nodulizing grade by audio frequency method. 介紹了音頻法檢測鑄件球化級別的原理及試驗結果。
