Minecraft wiki entry for Development_versions, associated text: Added sounds.
Has a shaking animation when hit or right-clicked.
Based on the position and facing, bells can only be hit in some certain directions, and will only shake in those directions.
Changed texture.
Changed model for ceiling bells and added models for wall bells.
Can now be placed on walls.
Changed block states face=ceiling|floor|wall to attachment=ceiling|double_wall|floor|single_wall.