Nonparametric Spectral Peak Modeling

Beginning in 1999, Laroche and Dolson extended IFFT synthesis (§G.8.1) further by using raw spectral-peak regions from STFT analysis data [143,142,139]. By preserving the raw spectral peak (instead of modeling it mathematically as a window transform or complex Gaussian function), the original amplitude envelope and frequency variation are preserved for the signal component corresponding to the analyzed peak in the spectrum. To implement frequency-shifting, for example, the raw peaks (defined as ``regions of influence'' around a peak-magnitude bin) are shifted accordingly, preserving the original amplitude and phase of the FFT bins within each peak region.