The musical composition heard by millions at the inauguration was actually an audio tape, recorded days earlier.
Carole Florman, spokesperson for the Join Congressional Committee on Inaugural Ceremonies, says it was too cold for the instruments to stay in tune, so the famed quartet decided to use the taped version.
It was 28 degrees at 12:00 pm, when Cellist Yo-Yo Ma, violinist Izhak Perlman, pianist Gabriella Montero and clarinetist Anthony McGill began their performance.
The song, titled "Air and Simple Gifts," was composed specifically for Barack Obama's inauguration, just before Obama took the oath of office.
Ceremony attendees with seats near the musicians could hear them play, but the instruments were not amplified.