The engine supports playing back stereo assets as spatialized and non-spatialized.
2D sounds are non-spatialized, but 3D sounds can be non-spatialized as well.
Stereo spatialized sounds generates a dual mono source perpendicular to your Listener Orientation spread apart from one another based on the Stereo Spread value on your Sound Attenuation settings.
High and low sound is difficult to evaluate in real life as well.
I recommend this video to understand the challenges involved in sound spatialization as well as the implications of utilizing HRTF processing:
And more information on HRTF: Head-related transfer function - Wikipedia