Phonograph Micrographs

Do you know how a record stores sound?

Since I’ve been teaching undergraduate survey courses in communication, such as media industries or media technologies, I’ve had to learn how certain recording technologies work. One of those is the earliest sound recording devices of the nineteenth century.

Sound is vibrational energy that displaces air. To record sound you need to capture those vibrations.

The earliest sound recordings, such as those developed by Édouard-Léon Scott de Martinville in the 1860s and later by Thomas Edison and Emile Berliner in the 1880s, are like fossils of those vibrations. A needle that fluctuates carves those vibrations into a surface: Scott used lamp black, Edison used tin, and Berliner used zinc and beeswax. Those sounds and their vibrations are preserved inside of these tiny grooves.

The other day, I saw this image on the Facebook page for Copyright, a house music group from the United Kingdom. If you’re wondering if I am all of a sudden listening to house music, don’t fret. I’m not. It was shared via Goner Records, a rock ‘n’ roll label and music store in Memphis.

The shared image is two magnified photos of a record-player needle riding the grooves of a vinyl record. But with most things people shared online, it’s hard to tell whether the image is real. It looks plausible, but I’ve been burned before on sharing other things that “look plausible.”

After a few minutes of searching the web, I found a more reputable source for magnified images of a vinyl record. In 2005, students in an optics class at the University of Rochester magnified several small objects to demonstrate the capabilities of a scanning electron microscope.

One of the objects they magnified was a vinyl record.

The grooves of a vinyl record magnified 500x. Image courtesy of University of Rochester: URnano.
The grooves of a vinyl record magnified 500x. Image courtesy of University of Rochester: URnano.
The grooves of a vinyl record magnified 1000x. Image courtesy of University of Rochester: URnano.
The grooves of a vinyl record magnified 1000x. Image courtesy of University of Rochester: URnano.

These look a bit different than the viral image I saw on Facebook, and they’re not marked up with explanatory text and watermarks. However, they show how sound in its physical form as ridges along an otherwise smooth groove.

If you’re wondering about more modern sound recording devices, such as compact disk, they did that, too.

The pits of a CD magnified at 20,000x. Image courtesy of University of Rochester: URnano.
The pits of a CD magnified at 20,000x. Image courtesy of University of Rochester: URnano.

This image is actually magnfied 20x more than the vinyl record. I’m guessing they did so to reveal a perceptible variation in the disk surface. Because a CD is a digital storage medium, you’re not looking at sound. You’re looking at representations of digital information, which in turn, must be converted back into vibrations that we hear as sound.

I’m glad these students magnified both a vinyl record and a CD, among many other things. If the prognisticators are correct in predicting that we’ll one day buy more vinyl records than CDs, we may wonder what the CD looked like, how it worked, and why we resorted to such a complex way of storing sound when a simpler solution[1] existed for over a hundred years.


  1. and superior with respects to fidelity  ↩

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