Group Delay Manipulation with the Giant FFT
Coherent temporal manipulation of sound in the group delay domain
The Giant FFT is a single DFT spanning an entire audio file that produces a spectrum encoding the complete temporal evolution of a sound. Creative manipulations in this domain have produced compelling results, but typically smear discrete events into sustained textures by disrupting the temporal relationships between frequency bins. This paper introduces a framework for coherent spectral manipulation in the “group delay domain”, where the derivative of the phase spectrum with respect to frequency makes the temporal center of gravity of spectral energy explicit at every frequency bin. By identifying spectral regions around amplitude peaks and grouping them by group delay similarity, spectral features can be displaced in time through uniform modification of their group delay. We demonstrate reordering of melodic events in synthetic and acoustic melodies, amplitude-proportional spectral displacement for creative sound design, and modulation of group delay for creating temporal copies of spectral features. These results show that methods of coherent temporal manipulation are possible in the Giant FFT domain without windowed analysis.
Paper
Apel, T. (2026). Group Delay Manipulation for Creative Sound Transformation with the Giant FFT. Proceedings of the 29th International Conference on Digital Audio Effects (DAFx26), pp. 19-24. PDF