> On 5 Aug 2026, at 03:20, QueueSevenM > <[email protected]> wrote: > > I believe your understanding is mostly correct. But I will clarify something > in case it didn't come through. A well-known property of the voice is that of > shape-invariance. That is, that the properties of each voice pulse are > roughly the same regardless of the pitch. >
That’s just a consequence of the vocal tract model. A real vocal tract behaves differently, the pitch / glottal pulse period has an effect on the formant, since the tension in the tissue and muscles has an influence on the geometry of the vocal tract. When doing pitch shifts using the Keith Lent algorithm, you need to resample the grains a bit to achieve a plausible result. You can try this out with the Vocal Transformer plug-in in Logic Pro, there you can adjust the formant shift, which controls the resampling of the grains. Best, Steffan (feeling like in a Edgar Hopper painting of a music dsp bar ….) > Importantly for this, one of those properties is duration. In this > theoretical model, the voice pulses are assumed to be infinite duration > impulses. Of course, in reality, the energy decays rapidly so most of it can > be assumed to be concentrated within a small time range. > > In the proposed implementation, the windows used for the reconstruction > process are actually quite large. So most of the window would actually have > almost no energy, and the main voice pulse only makes a small portion of the > window. The window size L is always constant, so a higher pitch means that > the amount of voice pulses that can be overlapping also increases. I referred > to that maximum as M. Anyway, most of this overlapping are actually very low > energy contributions. > >
