Formal:
* Concertgoers: This is the most common and neutral term.
* Audience members: This emphasizes their role as spectators.
Informal:
* Concert fans: This emphasizes their enthusiasm for the music.
* Music lovers: This highlights their general interest in music.
* The crowd: This is a general term for the people attending the concert.
You can also use specific terms based on the type of concert:
* Festival-goers: For people attending music festivals.
* Opera patrons: For people attending opera performances.
* Show attendees: A general term for those attending any type of performance.
The best term to use depends on the context and the tone you want to convey.