Inaugural organizers did not respond to requests for comment.
All inaugural music is pre-recorded in case weather conditions or other circumstances could interrupt the program.
The use of a recording is typical in big events. In 2009, cellist Yo-Yo Ma was questioned about "hand-syncing" for Obama's first inauguration. Ma said instruments weren't functioning properly in 19-degree weather.
Even in good conditions, producing good sound can be a challenge in a large open space.
Some artists choose to lip-sync. Whitney Houston's memorable performance of the national anthem in 1991 at the Super Bowl was sung to a track.
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