Tunable Bells

Placing a note block underneath a bell could shift the sound's pitch to the note block's frequency, allowing people to harmonize bells, create actual bell towers, and other fun stuff. Having the bell be tuned instead of the note block just having a bell variant would be a little more interesting since the tuned bell could be directly interacted with by the player with the alt-fire button, which would be easier to aesthetically integrate into builds and also would feel pretty neat to use.