Hi Group, The New Yorker Magazine for May 19, 2014 has an article,
"A Voice From The Past / How a physicist resurrected the earliest
recordings", by Alec Wilkinson.
Physicist Carl Haber uses a device called a SmartScope to scan
phonoautograms, cylinder and disc records even if they are too fragile
or damaged to play and converts them to audio. He uses 2D and 3D scans.
The article also mentions Kumaran Arul from Stanford University
Archive of Recorded Sound, who is a pianist, and his work to study of
the playing styles found on piano rolls. The article starts on page
50. The author's web address is http://newyorker.com/go/outloud
Jack M. Conway
Los Angeles, California, USA