Seems like there's three main methods: 1. Pinch the aperture shut 2. Shut off air flow with the tongue 3. Stop blowing For me there's a gradation from 1) which is very abrupt to 3) which rings on a little. I find 3) the most pleasing but only practical in slow phrases and phrase ends. Is there more to it than that? Obviously I've omitted kiss offs etc. Not asking about that kind of stuff.