I've never really used a mute on sax except for practicing. My dad had one in the case of the old 10M from his college days. Putting a mute on a sax like a 10M is like putting a governor on a big block Corvette, but dad said that when he was playing at Michigan State, the director required the saxophones to use a mute on certain parts. Anyway, I left the case open one day while practicing and I think the dog got ahold of the mute and that was the end of it. Most of them that I have seen are a felt material and look like a donut that fits into the bell. I've never used one on soprano, but I wouldn't think that it would fall out if it was placed inside of the bell. They're not very heavy and should fit inside snug enough not to fall out. I can see where it might be nice for soprano to take away some of the shrill overtones and give it a softer, more mellow sound. Of course, you could always just stuff a pair of socks in the bell! I've done that before too and it pretty much has the same effect! Jim