Voice speed adjustment ruling

If the situation is exactly as you have described—namely, that you create faceless YouTube videos, use only your own natural voice, and merely increase the speed of your recorded voice slightly (for example, to 1.1x or 1.2x) for better fluency or presentation, without using AI-generated voices, voice cloning, echo, reverb, or any other voice-altering effects—then such a minor modification is not inherently impermissible according to Islamic teachings.

This is because:

The voice being used is your own genuine voice.

The slight increase in speed is only for technical improvement and presentation, not for deception.

The essential nature of the voice remains unchanged.

No prohibited or impermissible audio effects are being added.

Therefore, if the content of the video is itself permissible according to Shariah and does not contain anything unlawful, then creating such videos and earning income from them would, in principle, be permissible.