The DFT is an extremely powerful tool for assessing the spectral characteristics of signals. In this lesson you will learn about a variation of the DFT called the short-time Fourier transform (STFT). The STFT is used for spectral analysis of signals whose frequency characteristics are changing over time. There are many types of signals with time-varying spectral characteristics. Music, speech, and radar are common examples. The STFT extends the power of the DFT and is an extremely useful method for the signal-processing practitioner.