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While some stand firm in their belief that she was performing live, many sources maintain that Beyonce was lip-synching along to "The Star-Spangled Banner" at the presidential inauguration. One thing is for certain, though: If Bey was indeed lip-synching, she was doing a damn fine job.

Or was she?

Performers lip-synch more and more often nowadays, and most of the time, they pull it off without incident. This could be because concert-goers don't care (seeing as how physically demanding and complex today's stage performances can be) or simply because they never notice. Why, then, was Beyonce's performance questioned? What exactly was it about Beyonce's singing that tipped off her critics?

We asked professional vocal coach Justin Stoney, the president and founder of New York Vocal Coaching, to outline the tell-tale clues of a faker. Here are his seven signs for spotting a phony:

#1. No Live Microphone Sounds

"Things like 'P's and 'S's tend to make a different sound in a live microphone than in a previously recorded track," explains Stoney, adding that these plosive sounds and the "pops" they produce are easier to hear in a live microphone. "There are usually some of these in a live performance," says Stoney.

#2. Early or Late Cutoffs

"Most people, when looking for lip-synching, are looking to see when the singer is coming in … but really, what to look for is [if they are] ending their phrases at the exact moment of the recording," says the expert. "Often, if someone is lip-synching, you will see them cut off the note a little too early or late."

#3. Invisible Vibrato

Stoney describes vibrato as "the stylistic shaking of the voice heard in sustained notes," and if you're hearing it, Stoney says you should be seeing it, too. "Often, a singer's vibrato will also appear physically," he says. "For example, Whitney Houston's jaw used to shake a lot. You see this shaking in the sides of the neck or perhaps the jaw, the larynx or the trachea. Not every singer has this, but most do. If you see it happen, the singer is likely singing."

#4. No Audible or Visible Breathing

"Good breaths for singing are usually toward the silent side. But, if you listen closely, they can usually be heard, especially in quiet phrases when the singer has the mic close to their mouth," says Stoney. "Also, breathing for singing takes a great deal of physical work. If the breath looks too casual, it may mean the person is not actually producing sung sounds. On the other hand, very good singers like Beyonce have a way of making things look easy. All this aside, singing breaths will be very active and not passive, even if they are relaxed. So it's good to take a look at a singer's body."

#5. Mispositioned Microphones

"A live singer needs to move the mic closer or further away during a performance," explains Stoney. "The movement of the mic — in terms of proximity from the singer's mouth — should be reflective in the sound in the venue. If there doesn't seem to be much difference in the acoustical changes … it may be lip-synching. In short, the mic movement should correspond with the singer's sense of their own volume control."

#6. Inconsistent Mouth Shapes

"Singers shape their mouths in different ways to produce acoustical and resonance effects in their own voice. If someone is singing, the brightness of their sound may correspond to the openness of their lips or mouth, whereas the darkness of the sound will correspond to a more closed-mouth position, or even puckered lips like an 'oo' or 'oh' vowel," explains Stoney. "You can tell if someone is lip-synching [when there is] variety in the sound itself, but their mouth movements don't line up with these acoustical changes."

#7.  No Pitch Problems or Rasps

"It is actually acceptable for there to be very minor pitch problems or notes that are slightly raspy in many pop/rock performances," believes Stoney, who stresses that these problems are not necessarily mistakes, but rather notes that sound a bit more "human" that others. "Even great singers usually have a few of these things happen in almost all live performances." Therefore, if there's a noticeable absence of these types of sounds, Stoney thinks you may be watching a faker. "A live performance actually benefits from not being too perfect," he adds.

Conclusions:

Stoney believes that Beyonce was, in fact, singing live at the president's inauguration, but feel free to judge for yourself using his expert advice.

Be careful at your upcoming Super Bowl gig, Beyonce — we're watching.