(NEXSTAR) – How does a Super Bowl performer manage to dance on beat, change costumes, wield props and dodge backup dancers—all while staying on pitch and not losing their breath? Sometimes, they don’t.

Some singers need to or prefer to rely on a backup vocal track when performing live to ensure an airtight performance. How can you tell if someone is lip-syncing? Sometimes, it’s blatantly obvious, like when their lip-sync is off and their mouth isn’t moving in time with the lyrics. Those are usually the performances that go down in history for all the wrong reasons.

Another easy way to spot lip-syncing is to watch the position of the microphone. If the singer is using a handheld mic, and moving it closer and further away while singing, you’d expect the volume of their voice to waver. If it’s constant throughout, they’re probably lip-syncing to a track.

You can also look to a singer’s vocal cords for signs they might be lip-syncing. If a singer is belting out a note with lots of vibrato, Slate suggests looking to their throat for signs of strain. If they’re really giving it their all, you should see some sign the vocal cords are working.

Listening closely to a performance will also give you clues to whether or not someone is lip-syncing. If their choreography is challenging, but they’re not even the slightest bit out of breath while running up and down the stage, you can probably bet it’s a lip-sync.

Vocal coach Justin Stoney told Fox News he pays extra close attention to the beginnings and ends of phrases to identify lip-syncing. “Often, if someone is lip-synching, you will see them cut off the note a little too early or late.”

Stoney also listens for P and S sounds in lyrics. Imperfections like popping Ps or slightly slurred S sounds can be signs of a true live vocal performance. Finally, if the performance sounds exactly like the radio version you’ve heard a million times, it probably is the exact same track.

Why lip sync? In a performance with so many moving parts, it can be the best way to ensure things go off without a hitch. “There’s too many variables to go live. I would never recommend any artist go live because the slightest glitch would devastate the performance,” Rickey Minor, who has produced multiple Super Bowl performances, once told the Associated Press.

Katy Perry admitted some of her vocal tracks were recorded for her 2015 performance, telling Reuters ahead of the show, “I think a lot of it will be live.” The Red Hot Chili Peppers said they did the opposite in 2014: singing live but using pre-recorded instrumentals. Their guitars weren’t even plugged in on stage, CNN reported.

Will this year’s halftime performers be lip-syncing? Keep a close eye on all five of them—Dr. Dre, Kendrick Lamar, Eminem, Mary J. Blige, and Snoop Dogg—to see if you can tell.