reverse engineering of acoustic sources

[beauchamp james w <jwbeauch@xxxxxxxxxxxxxxxx>]

In the Februrary, 2004 issue of Scientific American, Wayne Hu and
Martin White in their article "The Cosmic Symphony" write

  "...researchers have been able to use [temperature variations of
  the cosmic microwave background] to precisely estimate the age,
  composition and geometry of the universe. The process is analogous
  to determining the construction of a musical instrument by
  carefully listening to its notes."

My question is: Has there been any work in the second area? (I know
the reverse has been worked on.) Are the authors trying to say that
the cosmic quest is as difficult as the acoustic one, or as easy?

Jim Beauchamp
Univ. of Illinois Urbana-Champaign

PS I note that in their p. 48 figure they have the wrong series of
   acoustic standing waves.