The mystery surrounding Beyonce's National Anthem performance at U.S. President Barack Obama's inauguration on Monday (21Jan13) continues thanks to audio the Wall Street Journal has obtained direct from the singer's microphone.

Beyonce has yet to address claims she lip-synced the Star-Spangled Banner at the prestigious Washington, D.C. swearing-in ceremony - and representatives for the U.S. Marine Band who accompanied her appear to be mixed over the drama.

One musician, Kristin DuBois, revealed Beyonce was just mouthing the words to a pre-recorded studio version of the track, telling the New York Post, "All music is pre-recorded for the ceremony because there are so many eventualities and conditions that day. We performed, live, the band. But we received last-minute word that Beyonce was going to use the pre-recorded vocal track. Those were the instructions we were given."

And band director Colonel Michael J. Colburn revealed Beyonce only had one day to prepare for the gig since she has been busy rehearsing for America's Super Bowl half-time show next month (Feb13).

On Monday he told news website Buzzfeed, "As soon as we get information from the Presidential Inaugural Committee (about) who the guest artists are going to be, we make contact with them, find out how we can prepare arrangements that will really kind of flatter their voices - of course in the right key.

"Beyonce, she's getting ready for the Super Bowl, so we didn't have a chance to do anything with her until last night (20Jan13)."

Another band rep, Captain Gregory Wolf, has since played down the fuss, insisting, "No one in the Marine Band is in a position to assess whether (the performance) was live or pre-recorded."

And now the footage obtained by the Wall Street Journal appears to suggest Beyonce did sing the National Anthem live but used a pre-recorded track to bolster her vocals.