Method and system for implementing a Fourier transformation which is adapted to the transfer function of human sensory organs, and systems for noise reduction and speech recognition based thereon

摘要

In telecommunications, the Fourier transform is often the variant Fast Fourier Transformation, FFT short, for example, in processes for echo cancellation, noise reduction, to improve the speech recognition and to encode audio and video signals, is used. In the FFT, the number of frequencies N and the number of samples K are the same, the frequency spacing is constant, the bandwidth is constant, the delay between the time signal and the frequency spectrum is fixed. These properties do not allow adaptation, for example to psychoacoustic characteristics, the frequency resolution of the human ear is not linear. According to the invention a Continuierliche Fourier transform, short-CFT, indicated with the time function x (k) is displayed in the frequency groups, the number and size of the transfer function of a system to be analyzed is determined. The summation of the FFT is replaced by an integrator in CFT to give staff of the previous block processing a sliding Fourier transformation is made possible.