Formal:
* Audience - This is the most common and general term, especially in a performance setting.
* Spectators - Similar to audience, but emphasizes the act of watching.
* Applause - While not a noun, this word itself can be used as a collective term.
Informal:
* Claque - This refers to a group of people hired to applaud a performer, often used in a negative way.
* Raving crowd - This suggests a very enthusiastic and energetic group.
* The cheering section - This implies a particular group of people who are actively cheering and applauding.
Ultimately, the best collective noun depends on the specific context and the tone you want to convey.