It was not precisely lip-synching, but pretty close.
The somber, elegiac tones before President Obama’s oath of office at the inauguration on Tuesday came from the instruments of Yo-Yo Ma, Itzhak Perlman and two colleagues. But what the millions on the National Mall and watching on television heard was in fact a recording, made two days earlier by the quartet and matched tone for tone by the musicians playing along.
NYTimes.com has the story.