XPAND is a Motorola Solutions trademark for a feature found in it’s Professional Series of analogue radios. It’s purpose is to improve the perceived quality of received audio by gently amplifying quieter voices and gently reducing the level of louder voices.
These techniques are known as expansion and compression, or companding, and have been widely used in the military and music industry for decades…However adding this extra circuitry in the compact space that is a mass market portable two way radio was a challenge that no other manufacturer had taken up.
After the introduction in the late 1990’s by Motorola, many other manufacturers followed suit with similar systems.