Audio clip settings .. need math

Hello
It would be very helpful to understand the math used to divide sound between the speakers (or sum) for each of these two audio clip settings.

3D Sound If enabled, the sound will play back in 3D space. Both Mono and Stereo sounds can be played in 3D.

Force to mono If enabled, the audio clip will be down-mixed to a single channel sound.

In particular I need to know how the engine pans a stereo sound in 3D and how it sums stereo if Forced to mono.

Thanks !!