Just FYI, Luigi's Mansion was made with a 30 FPS lock, so the audio issue you're getting isn't a problem with Dolphin, it's just the game engine bugging out since it's being forced to run on a higher FPS. In other words, you'll probably need to patch something in the game to avoid this (e.g. a Gecko Code or similar)...
Avell A70 MOB: Core i7-11800H, GeForce RTX 3060, 16 GB DDR4-3200, Windows 11 (Insider Preview)
ASRock Z97M OC Formula: Pentium G3258, GeForce GT 440, 16 GB DDR3-1600, Windows 10 (22H2)
ASRock Z97M OC Formula: Pentium G3258, GeForce GT 440, 16 GB DDR3-1600, Windows 10 (22H2)