This alien has a very stuffy, nasally, and gruff voice, primarily because the character lacks a nose, resulting in a distinct congested sound. While nasally, the tone is deep and slightly gravely, matching his plant-like composition and the "rotten stench" associated with him. Voice reference: https://www.youtube.com/shorts/ooVJeAwjljA (If you have a voice modulator, use it for one of the takes)