The frequency pseudocolor-coded speech spectrogram is then obtained by means of a sampling narrow slit placed at Fourier plane in white-light optical spectrum analyzer.

然后在白光光学频谱分析系统中，利用放置在傅里叶频谱面上的取样狭缝得到按频率假彩色编码的频谱图。

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But audio experts say that the basic principles the CIA uses are likely the same ones that have driven the field of voice recognition since the 1940s: use of a spectrogram, a visual representation of the frequencies of human speech.

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