Beyonce's rousing performance of the Star-Spangled Banner during the presidential inauguration Monday has become a lightning rod for speculation: Was it lip-synced or not?

According to CBC News, the U.S. Marine Band confirmed in a statement that the musical accompaniment was pre-recorded, explaining that "there was no opportunity for Ms. Knowles-Carter to rehearse with the Marine Band before the Inauguration so it was determined that a live performance by the band was ill-advised for such a high-profile event."

Master Sgt. Kristin duBois earlier told news outlets that the band had been informed that Beyonce would be using a pre-recorded vocal track, but the Marine Band seemed to back off the suggestion that it was a straight lip-sync by Tuesday afternoon, saying in the statement that "regarding Ms. Knowles-Carter's vocal performance, no one in the Marine Band is in a position to assess whether it was live or pre-recorded."

A source very familiar with the situation tells CBS News that Beyonce performed the national anthem live, but she pre-recorded a track of the song to sing over. The source said this is a standard performing practice.

The source added that her microphone was on and her voice was audible and the pre-recorded track was for backup/safety purposes.

The Marine Band also said that all inaugural music is pre-recorded in case weather conditions or other circumstances could interrupt the program.