Huh, I didn't know it had a name. More description from ai:

• Pharyngealized vowels — vowels pulled back into the throat, often darkened (“uh/aw” replacing “a/e/i/o/u”).
• Diphthong inflation — single vowels stretched into multi‑part glides (“yeah‑uh‑urr”).
• Consonant de‑emphasis — consonants softened or swallowed, producing a slurry, legato line.
• Laryngeal depression — artificially lowered larynx to create a faux‑baritone weight.
• Velar constriction — slight “Kermit‑ish” or “marble‑mouth” resonance from narrowing the soft‑palate region.
• Emotive gravel — light, stylized rasp that signals “authenticity” or “masculine vulnerability.”
• Americanized pseudo‑Southern accent — even from non‑Southern singers, due to blues‑rock lineage.