The Invention of Stereo: Two Ears, Two Speakers

Before music was “on every corner” via iPods, iPhones, and smartphones, “stereo” was in practical use a word to describe almost any form of music player. It’s kind of like using “Coke” to describe virtually any bubbly, sugar-laden beverage. You know, like Xerox for copies and Kleenex for boogers. The invention of stereo was far more interesting than office equipment, so let’s dive in.

The word itself comes from the Ancient Greek term stereós, translating to something like rigid, solid or even three-dimensional. Hold that thought for a hot second because it kind of makes sense to describe what stereo is really all about.

Old Sound, New Sound

Recorded music dates back to 1877 (at least in practical terms) to Thomas Edison’s invention of the Cylinder Phonograph and Emile Berliner’s patenting of the gramophone, which used flat disks. At the time, Edison was looking for ways to capture and re-use information transmitted through the telegraph and telephone. A paper tape contraption was the idea behind “recording” a telegraph message, while to save audio, Edison experimented with paraffin paper and foil-wrapped steel cylinders. He figured connecting a diaphragm to an embossing needle would carry sound vibrations through the needle, creating textured grooves in the cylinders. A separate playback needle and diaphragm sent the groove patterns back through a playback diaphragm, and voila! His first test of recording “Mary had a little lamb…” worked.

After a few decades, the technology improved, and many homes had record players that performed the same basic functions as Edison’s Cylinder Phonograph but with flat discs. For purposes of this story, playback occurred through one single speaker and all sounds were combined in one output stream, what we refer to as “mono” or “monaural” today.

Not Very Surround Sound Movies…

The modern era of stereophonic sound, worshipped by hippies, Deadheads and audiophiles everywhere, actually began with the movies.

Alan Dower Blumlein was a sound engineer at EMI (Electric and Musical Industries), one of the largest record and music conglomerates around. The consummate inventor and tinkerer, Blumlein’s brain was still burning coal even when out for a relaxing night at the movies with his bride. After one such outing in 1931, Blumlein expressed frustration at the sound experience of the “talkies.”

With sound coming from a single speaker, a viewer might hear the leading man (on the left side of the picture) whispering sweet nothings to the leading lady while the sound came from a speaker to the viewer’s right. An extreme example, but it illustrates the problem of monaural sound. However you place the speakers, the viewer or listener’s brain won’t be able to triangulate the location of the sound with what they see on the screen.

Stereo Ear and Eye Processing

Just as a pair of eyes, combined with some brain matter, can estimate distance by “seeing” an object from two slightly different angles, that same brain can reconcile the origination point of a sound by hearing it from two different locations—the right and left ears.

If a tree falls in the forest somewhere off to one’s left, the sound waves reach the left ear just a fraction of a second before the same waves titillate the right eardrum. The brain, being smart, figures, “Hey, the sound is coming from a place closer to my left ear!” And our brains, even among those who watch the Kardashians, are sophisticated enough that we can detect gradients, so via differences in what and when the left and right ears detect sound, we can figure a sound is coming from the 10 o’clock or 1:30 direction. Voila! We’ve just described what audio engineers and folks who drop ten grand on a hi-fi system call a sound field.

Bottom line: in the real world, our brains can do a bang-up job of figuring out where each sound originates. Close your eyes while listening to a live orchestra, and you’ll be able to point to the location of each instrument.

Blumlein’s Stereo Innovations

While there were some crude “two-channel” initiatives dating back to the 1881 Paris Opera at the Paris Electrical Exposition, the beginning of modern stereo really began with a slew of patents from Alan Blumlein.

In his first batch, he came up with ideas we still use today, like circuitry to preserve directional sound, microphone use and placement for recording in stereo and the method we use to capture stereo recording information in vinyl record grooves. All in all, Blumlein came up with more than 100 patents related to stereo, surround sound and other sound-related technologies.

EMI did put the technology to use almost right away, recording “Jupiter Symphony” by Mozart at EMI Studios, later renamed Abbey Road Studios. The team led by Blumlein also created movies to refine the concept, solving Blumlein’s complaint of sound not following the actors on screen. One prototype film showed moving trains, complete with sound following the engines across the screen.

Death to Mono; Long Live Stereo

Like many innovations in the marketplace, it took some work for the public to catch on and insist on stereo sound for recorded music and movies.

Disney tried in 1940 with the release of their groundbreaking movie Fantasia. “Fantasound” featured multi-track audio recording played back through multiple speakers at specially-equipped theaters to render a form on stereo experience. Theater investment was significant, so the idea didn’t catch on.

It wasn’t until the late 1950s that record companies started to release stereo recordings, using the same “two-track” record groove technology Blumlein pioneered. As most consumers had mono record players, the two types of records had to coexist in retail channels for a decade, give or take.

During this time, clever marketers resorted to all manner of cool gimmicks like retail demo setups playing “moving sound” for curious consumers. RCA Victor even produced the stereo record Sounds in Space to capitalize on the space race frenzy.

A Tragic End to the Beginning

When World War II broke out, EMI talent was recruited to aid the war effort. Blumlein was instrumental in the development of a new navigation and target mapping radar system, the A2S. So, Blumlein’s talents weren’t at all limited to audio entertainment. Tragically, the war effort claimed Blumlein’s life—he was killed in June of 1942 in a Halifax bomber crash, which also destroyed the prototype A2S system.

The next time you break out the classic audio gear and listen to Dark Side of the Moon and marvel at how the “three-dimensional sound” moves around the room, remember that clever audio engineer from the 1930s—Alan Dower Blumlein.