Does rock band require a microphone in order to play like gh metallica or smash hits?

Rock Band does require a microphone if you want to play the lead singer role, but it's not limited to singing along with the songs. Harmonies, solos, and backups are all possible with the microphone, and in-game effects can be applied to further customize your performance. Even if you're not into singing, the microphone can be used for in-game commands as well.