Spectrogram

The sound spectrogram is one of the most fundamental tools of digital speech processing. The sound spectrogram of a speech file is an image map of the sequence of short-time log (or linear) spectrums, where each spectrum is obtained from an STFT analysis of a frame of speech, and subsequent spectrums are obtained from STFT analyses of subsequent, highly overlapped in time, frames of speech. Thus the sound spectrogram is a two-dimensional (image) plot of speech spectral information (linear or log magnitude) over the duration of the speech signal.