Placing wool on top of a note block reduces the volume by 50%

Placing wool on the top side of a note block would dampen the note to being half as loud.

Currently, it is impossible to control the velocity of a note block (besides placing the block further away from the player). Adding this would easily allow more creativity with note block contraptions while also reinforcing the mechanic of vibration dampening with wool.

Additionally, placing white (undyed) wool would reduce volume by only 25%, while black (densely dyed) wool reduces by 75%.