Another organizing convention was the "celestial sphere," an imaginary globe thought to surround Earth. Like a traditional globe, the celestial sphere possessed north and south poles, an equator and coordinates similar to latitude and longitude. To an observer on Earth's surface, stars existed as ...
Things like behind, up or down are not happening with stereo to binaural processing, because we are using HRTF IRs for left and right channel sound sources positioned in front of listener (the azimuths 30 degrees left and 30 degrees right from OP...
If your first azimuth is too small to subtract 180 degrees, just add 180. For example, if your azimuth was 40 degrees, you know that you cannot subtract 180 degrees from it, so add 180 (40+180 = 220 degrees). Remember, a back azimuth goes in the opposite direction from the azimuth....
a horizontal angle is often calculated between two lines of sight. For example, if a person is standing atop a hill and looks out at two separate landmarks, the horizontal angle would be the angle between his line of sight to object ...