It's a groove thing.

I don't want to downplay genuine discovery, but your story about optically reading old records left me a little underwhelmed ("Groovy Pictures: Extracting sound from images of old audio recordings," SN: 5/29/04, p. 339). The optical playing of records has been available in the commercial market for several years. Just do an Internet search for "laser turntables."

JERRY BOEHM, SCHENECTADY, N.Y.

This is not an especially new invention. A commercial laser model capable of playing vinyl records (all sizes and speeds) in high fidelity has been available for at least the past 13 years. I suspect that the laser system is even more adaptable to measuring vertical trajectories in wax cylinders than a confocal microscope is.

NEIL GOODELL, LAS CRUCES, N.M.

Unlike laser turntables, the groove-mapping technique described in the story yields a copy of all the topographical information in the original recording's grooves. Once preserved, those contours remain available as new and better methods of sound extraction are developed. Moreover, by graphical means, a restorer can lift scratches and other damage from the virtual surface.--P. WEISS 

The article reminded me of an idea from an old friend: It might be possible to re-create sounds of the distant past from pottery that was turned on a wheel. The ambient sounds (e.g., discussions between potter and client or apprentice) may have been recorded on the surface of the pot as it turned, particularly if the potter used a sharp metal tool in a last operation to smooth the surface. It might be worth a listen.

WARD HALVERSON, CAMBRIDGE, MASS.