Look in the manual, page 21 in the European manual, it tells you how to turn it on and off and have it quiet, medium or loud. It is called "Melody" and appears under the "Setup" menu.
I just bought an LN46A650 LCD HDTV. Whenever I power it on, it plays an audio "jingle" that I find irritating. Anyone know how I can permanently turn this off? I've searched the forum but not found any correspondence on this topic. Appreciate help.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic