Efficient computation of the short-time fast Fourier transform

The short-time fast Fourier transform (STFFT) is an important tool in speech and other time-varying signal processing areas. The STFFT is often required to be performed in real time, which makes it important that computationally efficient methods exist. Traditionally the STFFT has been computed by repeated application of the fast Fourier transform (FFT) at consecutive time instances. This method does not utilize the redundancies that exist between the FFTs at different times, which, especially for small time differences, are quite large. A method for computing the STFFT is described which utilizes the redundancy to reduce the number of operations required to compute the STFFT. The reduction depends on the length of the STFFT and the time difference between FFTs. This method is more efficient than the regular FFT method for up to very large time differences