Question about async audio emulation.

[herpderpus]

I have noticed that in older versions of the emulator, for example 3.5 stable, sound doesn't break up when framerate drops below 100%, while in newer versions it happens all the time. A game where I notice this a lot is Kirby Epic Yarn, as soon as the emulation slows down even of a couple of frames below 60, the music starts to skip and pop like crazy, while on 3.5 the music plays normally even if the framerate drops.

I'd like to know if this is normal, and if there is any way to restore old behaviour in newer version of the emulator. Or maybe it was removed for accuracy reasons or something? If that's the case, I'd like to know what's the most recent revision that still plays audio asynchronous from the video.

Thanks in advance.