(NEXSTAR) – Super Bowl halftime shows have turned into major productions involving complex choreography, moving sets and surprise cameos. How does a performer manage to keep up with all that and still hit the right notes? Sometimes, they have a little help.

Some singers need to (or prefer to) rely on a backup vocal track when performing live to guarantee a flawless vocal 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-syncing, 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.

Beyoncé didn’t lip-sync during her memorable Super Bowl performance in 2013, but she did admit to lip-syncing just a few weeks prior during another high-profile televised event: The singer said she decided to rely on a vocal track while performing the national anthem on President Obama’s Inauguration Day.

“I practice until my feet bleed and I did not have time to rehearse with the orchestra,” she said in a 2013 press conference. “Due to no proper sound check, I did not feel comfortable taking a risk. It was about the president and the inauguration, and I wanted to make him and my country proud, so I decided to sing along with my pre-recorded track, which is very common in the music industry. And I’m very proud of my performance.”

Will Rihanna be lip-synching during this year’s half-time performance? Keep an eye out on Sunday to find out.