Today, a cornucopia of sound. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

It's no surprise that modern recording studios owe their existence to electrical power. Signals from microphones are amplified, computers store and manipulate sound files, and specially powered speakers recreate recorded sound. Yet for decades the recording industry operated without any electricity at all.

David Pitman in the News 88.7 Control Room (Houston Public Media)

At a basic level, recording really isn't all that complicated. When we speak or play music we create sound waves. Recording requires a device for capturing those waves. Playback requires a means of converting the transcribed waves back into sound.

Thomas Edison famously found a means of doing this in 1877. He wrapped tin foil around a cylinder. While the cylinder turned, a needle etched the waves produced by Edison's voice into the foil. A second needle recreated the sound by retracing the path carved by the original.

An Edison Phonograph (Wikimedia)

The turning cylinder was powered by a handwound spring. And that was it as far as power. Amplification — where most of today's power goes — relied entirely on acoustics. In practice this meant cones, very much like the cones held by yell leaders at sporting events. Instead of using a microphone, sound was channeled through the large end of a cone. At the small end was a diaphragm that vibrated to the sound waves and moved the recording needle. The setup made for interesting recording sessions as performers crowded around the front of a large horn — many large horns when multiple recordings were made. And since only a handful of cylinders could be recorded at one time, studio musicians played repetitively, often for hours. Not all instruments were well suited for these early recordings. Which did the best? Those that were loud.

A collection of acoustic horns at Thomas Edison National Historical Park, in a research lab next to the music room. (Wikimedia)

Playback was much the same as recording, but reversed. The bouncing needle jiggled the diaphragm at the small end of the horn and the sound waves were amplified as they moved to the large end. Unfortunately, there were limits on how much sound the small, vibrating diaphragm could generate, and similar limits on how much amplification a cone could provide. In short, it was tough to turn up the volume.

It took a full half century from the time of Edison's invention for the recording industry to go electronic. It's not entirely clear why it took so long. Alexander Bell demonstrated a functioning telephone one year before Edison made his recording; and Bell's telephone was entirely electric, converting sound waves to electrical signals and back again. The rudiments of electronic recording were there all along. Still, it wasn't until the late 1920s as commercial radio hit its stride that the recording industry finally chose to embrace electricity. The time had apparently come.

The days of recording without electricity are long gone. But they're not forgotten. Replicas of acoustical horns are the most coveted prize in the music industry — at least when they come in the form of a Grammy award.

Photo of a Grammy Award (Wikimedia)

I'm Andy Boyd at the University of Houston, where we're interested in the way inventive minds work.

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Notes and references:

Early Recording Sessions. From the website: http://www.tinfoil.com/record.htm. Accessed May 6, 2014. Has some excellent pictures.

History and Types of Loudspeakers. From the Edison Tech Center website: http://www.edisontechcenter.org/speakers.html. Accessed May 6, 2014. Has some excellent pictures.

This episode first aired on May 8, 2014.