I was asked to extend my repitching experiment by comparing the 96kHz performance against 48kHz performance in Hauptwerk 7. I did the same as yesterday: loading pure sine wave of 2kHz into a Hauptwerk "pipe". Holding the pipe sounding while rising the pitch of the pipe gradually to +50 cents, then resetting to 0, then lowering the pitch gradually to -50 cents, then resetting again to 0. I was using the Hauptwerk native pipe voicing for this, dragging the pitch slider up and down with a mouse.
I recorded at +20dB compared to yesterday, to make the vizualizations brigher and more instructive. And the audio was really very very loud. I was trying to listen to it, but I could not bear the sound. I will NOT publish the recorded wave audio this time, because I do not want to damage your ears. I only publish the spectral visualizations.
Here the results:
1.) Hauptwerk 7, using the "lower" audio processing quality. 96kHz on the left, 48kHz on the right.
Observe huge amount of harmonic distortion and aliasing in both cases. 96kHz sample rate introduces, however, exactly half the amount of the generated harmonic distortion and aliasing. These artifacts introduced by the Hauptwerk repitching algorithm are clearly audible at normal listening levels. You hear especially the tones introduced below the sine wave, while the harmonic content above the sine wave makes the sound subjectively more pungent, or brighter. This is known phenomenon from the times of Hauptwerk 4, I described it already in 2013. The lower quality audio processing of Hauptwerk 7 seems to be the same as the audio processing of Hauptwerk 4.
2.) Hauptwerk 7, using "medium" audio processing quality. 96kHz on the left side, 48kHz on the right side.
Observe far less harmonic distortion and aliasing introduced, again, 96kHz gives rise to exactly half of the distortion of the 48kHz. Nevertheless, I could not hear the distortion at normal listening levels, and at +20dB, I was unable to bear the sound, so, I could not judge. The "medium" processing quality is OK to me at both sample rates (96 or 48 kHz), because it does not introduce an audible distortion or aliasing when repitching.
3.) Hauptwerk 7, "higher" audio processing quality. 96kHz on the left side, 48kHz on the right side.
Honestly, I do not see (and do not hear) much difference compared to the previous "medium" quality. Everything said about the previous recording, is also true about this recording. Again, I cannot hear any distortion when listening at normal listening levels. I think this is a superb result of the audio processing quality.
What to say at the end of this experiment? Avoid using the "lower" quality of audio processing when possible. At both sample rates, 96 or 48 kHz, audible distortion and aliasing is introduced when repitching. I recommend using the "medium" or "higher" audio processing, because these offer clean audio with no audible distortion or aliasing at both 96 and 48kHz.