Going through all my news links and theres been a news update for the PCSX2 emulator which is of course a PS2 emulator not only for Windows but other Operating systems also, this time they chat about the implementation of PSX emulation, heres a tidbit:

Previously, PCSX2 had always failed to play PSX games due to unimplemented devices that are necessary for backward compatibility. Rama had then decided to reach out to other developers to fix the problem. However, most of the PSX games still suffered from bad audio and the source of the issue was the SPU2 plugin. It was assumed that in the backward compatibility mode of the SPU2, the hardware provides a mapping window into SPU2 RAM, which wasn't properly handled by the plugin. Pseudonym then fixed all the issues related to the mapping management and SPU2-X started providing much better results. At this time, he also redid the reverb algorithm (which is shared between PSX and PS2 modes) and improved it significantly towards an exact replica of the original.

Theres a multitude of news so head on over to the official site here --> http://pcsx2.net/281-q4-2016-progress-report.html