It’s still on my to-do list to start working with audio triggers for basic rotation stuff (riptide, healing rain, healing stream). Currently I configured them to ‘show and glow’ when I’m not using them on cooldown. However, I do see audio as a configurable option (WeakAura Options > Actions >Play Sound). How that should work exactly I don’t know, as I haven’t actually configured it myself yet.
I do think audio is a great (subconscious) trigger to use. Selecting the right sounds can be challenging though. It’s especially great because it cleans up the need for information depicted on your screen. Fun to see I’m not alone with that thought.