http://www.youtube.com/watch?v=ngpx84g1Cfo

That's a video of a man playing music with water glasses. Some are filled higher than others, but they all play.

Warning - the video is loud. turn down your volume for it.

Clearly the answer to "Do empty vessels make the most noise?" is "It depends on the resonant frequency of the vessel."

FYI, I have a wok and its lid which hang on a rack over my stove. When the stove is really going, the lid starts to swing, and when it hits the wok, it produces a low and rather pretty musical note. We like it.