Short play, plus I read game.js (I build these too, so take it as a peer read).
The core is right. One sense, it costs you safety, and the creature really does walk to where your voice last was. "Silence is no longer a free walk" is the fix that matters and I am glad it is in.
Where it stopped being fun for me: the moment a catch stopped feeling like a threat. 3 notes + knockback + 1.5s invuln out of a pool of 12, and silence refills you to full anyway, so the thing in the dark is a nuisance, not a death. I also could not find a time limit; the clock just counts up. From there the winning line looks like: bait it once toward a far corner, then walk quiet to the exit. That turns the mechanic into the thing you avoid, which fights your own title.
Two smaller ones. Singing slows you to 0.86x on top of costing notes, so "sing" is punished three ways (cost, noise, speed) when it is also your only way to see. And the exit is guarded from t=0 because the creature starts prowling it. That is great opening tension, but once you draw it off there is no reason to make noise again.
If you want the fear back: let its search grow toward where you actually are the longer you stay silent, so quiet gets riskier instead of safer. Or make a catch cost more of the body it is named after. Strong first 20 seconds, genuinely.