Short-time Fourier Transform and the Spectogram

The short-time Fourier transform computes a time-varying spectrum by applying the DFT to a windowed section of the data and sliding the window location through the entire record. This treats the spectral characteristics as constant within each window, but captures changes in the spectral characteristics by using different (possibly overlapping) window locations in time. The spectrogram is the magnitude of the short-time Fourier transform.