Time-frequency analysis with low numerical complexity using a t-f-mapping of the DFT magnitude

The short-time Fourier transform (STFT) or spectrogram data is the base for signal analysis in many computer music applications as resynthesis and sound interpolation. There is a tradeoff between time and frequency resolution due to the length of the analysis window used. This paper presents the modified moving window method, invented by Kodera (1976), which performs a time-frequency mapping of the DFT magnitude yielding a more concentrated energy distribution in the t-f-plane. A simplified method is proposed to overcome the computational complexity of the original version leading to the “improved spectrogram”. The resulting analysis data are used to form a parameter set of a sinusoidal signal representation which serves as the input to a resynthesis algorithm