Originally Posted by: dksuchardaThis might sound trivial but when playing my electric guitar I hear the open string note out of the speaker when I lift my finger.

Rusty has already provided a great reply! I'm just here to confirm that advice. :)

This is all about muting technique. The trick is that when you lift your finger, do not lift it off the string. Remain in contact with the string with either your fretting or picking hand so that you will mute any unwanted sound.

Hope this helps! Best of success!