Resynthesis analyses a real instrument recording into partial tracks and uses those measurements to set additive synthesis parameters

Resynthesis extracts the additive parameters of a real instrument by: (1) sampling the instrument at a note, (2) computing time-windowed FFT spectra at regular intervals (e.g. every 20 ms), (3) detecting and tracking spectral peaks across time windows, (4) measuring amplitude and frequency envelopes per peak. The resulting data specifies every partial’s amplitude and frequency trajectory. These trajectories are then mapped to additive synthesis envelopes. The process is automated in modern tools but can be done manually from spectral plots. Manual resynthesis is very laborious; even computers struggle with peak tracking when peaks widen, merge, or appear/disappear between windows.

Examples

In the chapter: piano sample -> Cool-Edit spectral analysis at 50 ms windows -> measure peak amplitudes in dB -> convert dB to mixer levels (Table 6.1) -> set sine-bank oscillators -> group partials with similar amplitude curves -> use multi-stage envelopes per group.

Assessment

Describe the four main steps of a manual resynthesis workflow from an audio sample to a functional additive synthesis patch, noting at least two common difficulties.