Soundbending is a special subset of techniques within Airbending that allows an Airbender to sonokinetically generate sound waves and manipulate already existing ones as they travel through the air. It was developed by Avatar Aang. Aang remains the only avatar who has used soundbending.
Sound is merely air that has been vibrated and sophisticated, and can pass through anything but it mostly travels through the air. The key to Soundbending is a combination of flexibility and endurance, finding and following the path of resistance as well as enduring enemies' attacks until the right opportunity to counterattack reveals itself, then striking with unyielding force. Soundbending's strength is its offensive capabilities which, rather than supporting a separate set of defensive methods, are transformed into defenses and opposition - offense into defense.
Soundbenders can overwhelm many opponents at once with large and powerful attacks that could prove fatal; however due to the pacifist nature of the Air Nomads such attacks are rarely used. Just like Waterbending and Earthbending, Soundbending has a distinct use of offense and defense. Instead of sacrificing defense for more powerful offensive tactics or allowing defense to become offense, Soundbending transforms offense into defense, utilizing positive and negative jing.