I've recently been noticing a few strange noises emitting my instrument and wondered if anyone could help. Since an embrochure change a few months back, when I play middle d's, my instrument starts rattling. I'm not sure whether this is down to me, or something wrong with the instrument, but its very annoying. And even more annoying, when I play a's and b's, I make a really weird growling noise, like I'm playing from the back of my throat. It's easy enough to control if I play quietly, but anything above mf results in a really weird sound. I've no idea how to stop it and any other notes are fine, but it's starting to get on my nerves! Anyone got any suggestions???