It really dampens the sound a lot! The neighbors best friend. I am very happy with it, and it does what it should. But I will say that it doesn't just take away the volume, but also the bass. I used it almost all the time, and I must say that it wasn't too fun having a C-string losing so much bass sound. I heard it on a violin, and that sound felt more natural, but kills a bit too much bass on the viola to enjoy the sound. So perhaps be aware of this trade off.