My buddy and I play on a server with this mod and came up with the hilarious thought: when shrunk, player's block sounds (such as anvil hits, tool usage, walking, etc) should be pitched according to their shrunken size.

Small players should make higher pitched sounds, and larger ones lower pitched.

I'm not sure if it's at all possible for you to differentiate which sounds happened as a result of a player's action, and intercept and modify them before getting sent to all the players around, but I think it would improve the shrunken player experience

This, but also for entities that you size up/down with left click.