[newamerikangospel]

Knocking will cause it to move once, whereas freq. waves are similar to that of ocean waves, in and out in at a specific speed. My guitar will sound like it has a crappy chorus effect on it (not plugged in) on Es and sometime G#, because my straplock rattle alot if there is no tension.

Pluck the strings when it is on a table and move your ear from the headstock to the bridge. Try to find where its the loudest. Start depressing items with your fingers, that may be loose. It may be your trem arm, it may be your pickups, straplocks, ect.

Oh and if it is rattling at the top fret (22nd, 24th) its not fret buzz (since there are no other frets for the string to come in contact with during its oscillation)