I've been thinking lately why airbenders don't have any special form of bending like metalbending or bloodbending and I came up with soundbending.
So the idea is that advanced airbenders can make the air vibrate to make diffrent tones. It can be used as a cultural form by making music and it can be used in battle by creating sonic booms or annoying high pitch sounds and stuff.
As for the discovery, perhaps Jinora or Ikki can become really skilled in making music later in life and she starts looking for other ways to make music, then she discovers soundbending.
So what do you guys think? Leave your thoughts about it in the comments or perhaps you have an even better idea for a special form of airbending