I wish to do a voiceover. The processed audio should sound deep, grainy. Unfortunately, I don’t have a deep voice. I tried several VST plugins. Eventually, they all sound fake or demonic. The pitch shift is better in Cubase with some success.
Next, I tried to model the human vocal tract. I tried splitting the audio into two channels. To the first channel, I added an audio chopper with a chopping triangle wave at 28 Hz. This is somewhat how the vocal cords distort in our vocal tract for deep-voiced people. This output was again made to go through a low pass filter of 1000Hz because the grain mostly affects the base voice and not the high-frequency sibilance sounds like T, F, P sounds.
The second channel was added to a high pass at 1000Hz allowing only sibilances to pass. The result was interesting, but there was something wrong. Some Uncanny valley in human listening.
Years ago, I did this quite a bit, changing voices(for games and edu stuff).
Convincing results depend quite a bit on a particular voice. Some sound great, others(with lots of noise components)not so much.
A female speaker with whom I worked quite a bit was great for this, I could make a convincing man from her, but she had to adapt her manner of speech otherwise she sounded too much like a girlish cartoon or comedy character.
She found this an interesting challenge, and became quite good at this.
Just tried this and it worked pretty well. Sounds a touch odd, but it’s for a comedy bit, so that’s okay. Key for me was not to move the pitch or formants too much. A 4th/5th was excessive against my voice.
there are plenty of options out there for hire.