拍頻
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差頻(英文:beat note或beat frequency)一詞源於聲學上兩個頻率相近但不同的聲波的干涉,所得到的干涉訊號的頻率是原先兩個聲波的頻率之差的絕對值,因此叫做差頻。這個概念也用到了光學和電子學中,指兩個頻率不同的訊號進行合波後得到頻率為兩者之差的新訊號。[1]
且因為頻率只是略有差異,在此假設
令
在此又令:
故y可以改寫成
註釋
- ^ Levitin, Daniel J. This is Your Brain on Music: The Science of a Human Obsession. Dutton. 2006: 22. ISBN 978-0525949695.
延伸閱讀
- Thaut, Michael H. Rhythm, music, and the brain : scientific foundations and clinical applications 1st in paperback. New York: Routledge. 2005. ISBN 978-0415973700.
- Berger, Jonathan; Turow, Gabe (編). Music, science, and the rhythmic brain : cultural and clinical implications. Routledge. 2011. ISBN 978-0415890595.
外部連結
- Java applet (頁面存檔備份,存於網際網路檔案館), MIT
- Acoustics and Vibration Animations (頁面存檔備份,存於網際網路檔案館), D.A. Russell, Pennsylvania State University
- A Java applet showing the formation of beats due to the interference of two waves of slightly different frequencies (頁面存檔備份,存於網際網路檔案館)
- Lissajous Curves: Interactive simulation of graphical representations of musical intervals, beats, interference, vibrating strings (頁面存檔備份,存於網際網路檔案館)
- The Feynman Lectures on Physics Vol. I Ch. 48: Beats
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