Why do professional singers wear earpieces on stage?

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Tags

1. #singer
2. #example
3. #singing
4. #drummer
5. #which
6. #especially
7. #monitor
8. #allows
9. #yourself
10. #noise
11. #earpiece
12. #called
13. #onstage
14. #there
15. #wants
16. #exactly
17. #shout
18. #louder