Unless you were one of the fortunate few sitting within earshot of the celebrated performers, what you heard was a recording made two days earlier.
Cellist Yo-Yo Ma, violinist Itzhak Perlman, pianist Gabriella Montero and clarinetist Anthony McGill made the decision a day before Tuesday's inauguration to use a previously recorded audio tape for the broadcast of the ceremonies.
Carole Florman, a spokeswoman for the Joint Congressional Committee on Inaugural Ceremonies, said the weather was too cold for the instruments to stay in tune.
"They were very insistent on playing live until it became clear that it would be too cold," said Florman in a telephone interview Thursday night.
People sitting nearby could hear the musicians play "Air and Simple Gifts", written for the inauguration by John Williams, but their instruments were not amplified.
"It would have been a disaster if we had done it any other way," Perlman told The New York Times, which first reported that the music was taped on its Web site Thursday. "This occasion's got to be perfect. You can't have any slip-ups."
The Marine Band, the youth choruses and the Navy Band Sea Chanters performed live, Florman said, although Aretha Franklin was accompanied by taped music and voices.
Florman said all the acts "laid down tape" before Tuesday's inauguration. When they did their sound checks on Monday, all but the quartet made the decision to have their live performances broadcast.
The temperature hovered around 30 for the ceremony on the Capitol steps, too cold for McGill's clarinet, Ma's cello or Perlman's violin to offer true pitch. But the cold played havoc with the piano, which can't hold tune below 55 degrees for more than two hours, Florman said. The group played at 11:43 a.m., and guests seated near them could hear them as well as the tape made two days earlier. Guests seated farther away, the crowds that thronged the National Mall, and the millions who watched around the world heard the taped version of Williams' piece.
"This isn't Milli Vanilli," Florman insisted, referring to the late 1980s group stripped of a Grammy for lip-syncing. "They had to perform in such cold weather, the instruments couldn't possibly be in tune. They were able to play in sync with the tape. It's not unusual."