From The TimeSplitters Wiki

Lasergun Noise Glitch
Requirements	Lasergun
Finder	Nevar00

If a player charging the Lasergun gets killed, the charging sound may continue after the player's death. The Lasergun sound will get stuck in the specific spot where the player with the Lasergun died, so the closer you are to that spot, the louder the charging sound is. The only way to turn off the sound is to end the match. A similar glitch happens with the Minigun.