Growing up all of our cats had bells on their collars. One of our males was the worst hunter ever, and it made a ton of noise, but we had a female, who was a good hunter before the bell. All the bell did was turn her into a SUPER silent deadly ninja assassin hunter. I remember checking to see if the bell was broken on numerous occasions as child because she was so silent. The only time the bell made a sound was if she wanted to wake you up by shaking her head next to yours when you were sleeping. Each spring we would have presents at the door step daily until any living thing was either dead, or had moved. Now my mind may have glorified this childhood memory somewhat, but I watched this cat take out a bird mid flight by leaping what seemed to be about 7-8ft straight up in the air, and creating and eruption of feathers, and again I don't remember a sound from the bell.