Updated: November 17th, 2005
The question often is: "Does an open hole flute effect the tone quality." The real answer: "No."
Many people will try to convince you otherwise, but that is just because most intermediate models are open hole. (Disagree? Please contact me and tell me why.)
My former professor at the University of Northern Colorado had the holes in her flute covered back up. She is now able to play quicker and cleaner because she doesn't have to worry about covering the holes.
You can use plugs to cover up the holes on an open-hole flute for beginners. This is good for beginners however the distance between keys and the head joint is different on open hole flutes and closed hole flutes. This means that if you use all the plugs on your open hole flute the tuning will be different than that of a closed hole flute.
I use the holes with my professional flute when playing jazz so I can slide from one note to another.