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Hello! I was wondering if anyone has some information to help me implement 'fake' noise in my SPC driver.

By 'fake' I mean the noise that doesn't use the actual SPC noise generation hardware, but rather exploits some kind of bug in the Gaussian interpolation (I think?). Chrono Trigger uses it a lot (for wind.. etc)

I want to use this noise along with a few other simple waveforms for synthesizing sound effects.

I studied that a lot in the past, and it ended up as a headache. Also, I didn't know as much math back then than now.

You basically need a sample using BRR filter 2 (or 3), and make the resulting waveform "overflow" from the normal 16-bit range, and that looping. You can get various noises that way, but honneslty, it takes a lot of trial & error to get anything that doesn't loop too often. Also uses modern SPC players like SNESAmp by Anti-Resonnance which is accurate. Many older SPC players / emulators are innacurate, and will either not produce noise (breaking Chono Trigger's wind) or simulate "perfect" white noise instead of the pseudo-noise the sample does.

So for the short answer, convert a sine wave into BRR, increase the shift amount (higher nybble of first BRR byte) and listen to the result.

Hmm, sounds like this isn't going to be easy..

I guess I'll have to setup some method to test various samples easily.

Well it's not really hard after you understand how BRR encoding works.
Read this, it's easy to understand but it's half-accurate.
A more complete version is this.