The pan and elevation elements allow placing of sound in a 3-D space relative to the listener. Both are expressed in degrees ranging from -180 to 180. For pan, 0 is straight ahead, -90 is hard left, 90 is hard right, and -180 and 180 are directly behind the listener.
The
<pan>element.The pan and elevation elements allow placing of sound in a 3-D space relative to the listener. Both are expressed in degrees ranging from -180 to 180. For pan, 0 is straight ahead, -90 is hard left, 90 is hard right, and -180 and 180 are directly behind the listener.
See
https://www.w3.org/2021/06/musicxml40/musicxml-reference/elements/pan/