To eliminate all sound you need it to have a good fit between wall and frame or foam filled gaps. you will then need sealable but openable inner secondary glazing about six inches apart from the external windows.
I've just tested mine, turned on telly in conservatory right by the bedroom window gone in to the bedroom and jcan ust about hear it going right up to the window, and it up quite loud. So low noise you'll have to live with it. Not satisfied and recently fitted call them back.
Bob, April 2009
