Interesting! Thank you for pointing that out!
I haven't tested it in MESEN, but it sounds to me like it has the same audio issue as the emulator that was used to make the web build. Personally I've had the best Game Boy audio results with BGB emulator. Unfortunately a staggering number of game boy emulators have poor audio for the 8-bit sound effect samples, which is the primary focus of this project 😂