心音信号是一种典型的非平稳信号，短时傅立叶变换(STFT，又称窗口傅立叶变换)是用于对非平稳信号进行时频分析的有效工具。
Heart sound is a highly nonstationary signal, and the Short-time Fourier Transformation (STFT) is an effective method for this kind of signal to be analysed.
快速傅立叶变换、滑动窗口和某些Linux音频编程可以为您提供符合您所选语言的音调识别能力。
Fast Fourier transforms, sliding percentage Windows, and some Linux audio programming can give you tonal-recognition capabilities with your language of choice.
你可能会问，我们为什么不像傅立叶变换用无限长的窗口一样，而在快速傅立叶变换中却用有限长的窗口进行分析呢？
You may ask, why don't we make the length of the window in the STFT infinite, just like as it is in the FT, to get perfect frequency resolution?
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