Walter Essex compares various recordings, with individual studies of the chorus and solo parts; liking parts of all of them, he is most fond of Barbirolli.

The sound section compares recordings on different media, from early-20th-century wax cylinders to modern CDs.

IMO the only good ones are where you want someone to compare different recordings, or are looking for an in-depth, scene-by-scene analysis.

They compare recordings you don't even remember having cut.

To the Editor: In his review of "The Compleat Conductor" (Aug. 24), Paul Griffiths writes that the author, Gunther Schuller, spent "many hundreds of hours" comparing recordings of significant conductors.

I'll use it to compare different recordings of the same piece of music, movement by movement.

Curators and collectors searching for source material, or simply the best-sounding copy of a concert recording, were required to spend considerable time accumulating multiple copies of the (supposedly) same material, comparing recordings, following up with sources, etc.

Most recently, the team of German researchers compared recordings of electrophysiological activity in the brains of 17 synesthetic subjects, who experienced color images upon reading letters or numbers, with recordings from 17 control subjects.

Mr. Buser recommends comparing recordings of a favorite song ripped at increasing data rates.

To the Editor: By comparing recordings that use profanity to a toxic-waste dump, William J. Bennett and C. DeLores Tucker (Op-Ed, Dec. 9) seem to believe that once someone is exposed to such material, the damage is real and irreversible.