I know this issue has been around for a while, but mine is slightly different. First off, here is what I have done to my PSP:

I followed the guide here:
www.LenGoldenstein.com » Howto: Install Custom Firmware on a PSP Slim – Introduction

I made a service battery and installed 3.90M33-3 firmware. I also installed the snes9xTYL 0.4.2 ME emulator.

I know others have had issues with save states loading with no sound. My issue is similar. I will be playing and save a state, and without even loading it the sound will either die completely or it will hang on one note continuously. This problem is not consistent. I am currently playing Legend of Zelda: A link to the past. This also happened with super mario world. So just saving the state will kill the sound. Loading that particular state will have no sound either.

This happens randomly. Sometimes I can go hours without it happening, other times it happens 4/5 times.

What I have tried:
There was a "fix" that involved loading a game with no known sound issues and saving a state, then without reloading the emulator go into the game I'm playing and save a state. That did not work at all.
I also saw on the readme in the emulator zip that "If you are having trouble with sound, try disabling speed hacks in the Hacks menu." That also did not work.

I installed the Euphoria emulator and not only was it really choppy, but I got a black screen when trying to access the map on Zelda. This did not happen with the other emulator.

Any advice? Better emulator? Thanks!