From the White Album to Yellow Submarine modern releases of the Beatles present their music in stereo sound. But this Christmas, hard-core Beatles fans will eagerly unwrap "The Beatles in Mono," an 11-CD box set designed to be played through only one speaker.
These days, we usually hear mono sound coming out of tinny telephone receivers, but that's not how this album sounds, said Alex Case, a professor of sound recording technology at the University of Massachusetts in Lowell. It will be more like unwrapping a newly-minted Beatles vinyl record and playing it for the first time.
During the 60s, the Beatles were not interested in stereo sound. They recorded each song on two tracks that were merged by their producer George Martin to be playable in monophonic sound, the standard of the day. Fans listened to the songs on mono record players and radio stations, which were almost all on the AM band at the time.
Some of these early albums were mixed for stereo sound, but this was an afterthought, hastily engineered for use on FM radio stations. During the 1980s, sound engineers created CD-quality sound in a lower-quality physical digital format, not a virtual digital format that most of today's music-lovers expect. Remastering technology was more primitive then, and could only create a slightly better sound than the stereo FM version.
Now this new box set digitizes the original analog tapes with mixing techniques designed to be more faithful to Martin's approach. Martin recorded the two main elements of each song -- the vocals and the instruments -- on separate tracks, so that one or the other could be emphasized in the music. Other sounds such as tambourines or clapping were recorded on both tracks, so that if, say, the drums were turned down, the other elements wouldn't be lost.
For the new albums, some corrections also had to be made because the master tapes have disintegrated over the years.
Another difference for U.S. listeners: these tunes are the original UK versions of the songs. Years ago, engineers remixing the songs for the U.S. added more reverb and echo, Case said. The new release goes back to the original UK versions, Martin's original mixes of the Fab Four.
© 2009 Inside Science News Service
Explore further: Explainer: How to solve a jewel heist (and why it takes so long)