It depends on the number of pawls, the type of springs, the shaping of the pawls, and the grease used. Even the alloy used for the parts makes a difference. I agree with BP, also, probably related to the more expensive hubs being made of good, strong alloys, the springs being stronger and in most cases, more pawls for a stronger, faster engagement. The old style freewheels were a totally different sound to me, from the current hub and cassette set up.

Bill