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Written by: Kevin Crane
Written on: October 6th, 2010
Tags: lifestyle, computer science, electrical engineering, material science
Thumbnail by: Van Veen/SXC.hu
About the Author
Kevin Crane is an undergraduate at USC majoring in Computer Science. His eclectic mix of academic interests includes music, robotics, and biotechnology, but he also enjoys water polo, guitar, and rock climbing.
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Volume XIII Issue II > Spread the Sound: A Brief History of Music Reproduction
Advancements in technology over the last 150 years have allowed people to spread music throughout the world by recording sound into a physical form and replaying it at their convenience. Music reproduction began in the late 19th century with the advent of the vinyl album, the first invention to let the masses record audio into a portable format. The vinyl album harnessed the complexity of sound waves by carving a waveform into grooves in a large disc. The next step in reproduction was the development of cassette tapes; using the same audio signals as vinyl records, cassette tapes selectively magnetized a continuous reel of tape, encoding music into a small compact package. Finally, the compact disc began its reign when digital technology advanced enough to allow the sampling and encoding of large amounts of music into an object about 1.2mm thick. These engineering marvels have allowed multiple generations to appreciate music and expand their cultural horizons with far more genres and bands than otherwise possible.

Music's Pre-Vinyl History

Scott de Martinville/Pisko
Fig​ure 1: The phonautograph, invented by Scott de Martinville in 1857.
Music has been a part of human history since the beginning of mankind. Initially, one had to be in the presence of the musician in order to hear the piece being played. With no way to reproduce or transport the songs, music was an entirely live experience taking place right then and there for the audience. Sheet music was invented in the 15th century as a method of notating exactly which notes should be played and for how long, enabling other musicians to replay what the composer created. Then, one orchestra could play the same song as another one across the country, but a live performance was still required to actually turn those notes into audible music.
The first device that enabled the recording of live music was the phonautograph (Fig. 1), invented in 1857 by Édouard-Léon Scott de Martinville, a French inventor. The device worked by funneling sound through a horn and then over a thin membrane, which was stretched tight like a drum. The membrane was attached to a small reed that engraved an image of the sound waves into a hand-cranked cylinder. While this device did not allow the user to play back the recording, it did set the standard for how to record music.
Bruderhofer/Wikimedi​a
Figure 2: The phonograph, invented by Edison in 1877.
In 1877, Thomas Edison advanced the idea of the phonautograph with his own invention called a phonograph, which allowed the device to replay the recorded sound (Fig. 2). His invention followed the same basic principles as Scott de Martinville's device, using a stylus moved by a vibrating membrane to etch waveforms into a rotating cylinder.
However, Edison's creation could also replay the audio through a reverse process. To replay, the needle would move based on the scratches in the rotating cylinder, vibrating the membrane to produce a sound that was amplified through a large horn. These cylinders were eventually replaced with 7-16 inch diameter flat discs called albums or records [1]. See our flash animation video (Fig. 3) to visualize the phonautograph's playback process.
Morton/Illumin
Figure​ 3: A how-it-works virtual museum featuring three notable music players in history: the phonograph, the turntable, and the cassette player. (Flash)

Vinyl Albums


The vinyl albums that many are familiar with today stemmed from this evolution of mechanical sound reproductions. The gramophone of 1889 replaced the rotating cylinder with a flat vinyl disc rotated beneath the recording needle. This change essentially finalized the now-common disc design seen in records everywhere. In fact, even today many people are still snatching up records wherever they can find them because of the high sound quality and accompanying collector's booklets [2].
So how is sound recorded onto vinyl albums? Sound is initially encoded into a soft material called lacquer using a sharp needle that carves spiral grooves into the circular base using a sound signal to guide it. Both sides of the lacquer are usually recorded upon in order to make the most use of the record's size. When all of the desired sound is recorded, both lacquer layers are placed on either side of a polyvinyl chloride disc and sandwiched together, fusing them into the final product.
Dydric and 32bitmaschine/Wikime​dia
Figure 4: A standard turntable. The record sits in the middle, and is read by a needle on the long arm (stylus).
The spiral grooves are the key to reproducing the recorded sound and replaying it for the user. The record is placed on a turntable (Fig. 4), a flat surface with a rotating shaft in the center and a stylus similar to that found on a phonograph. As the turntable rotates the disc at a constant speed (decided based on the type of record), the stylus tracks the spiral grooves, vibrating with the fine inscriptions recorded into the lacquer (Fig. 5). These vibrations are transmitted back up the stylus and amplified by a tightened membrane, producing sound into a cone-shaped horn (Fig. 3).
This basic technology has remained the same for years, apart from a few minor changes along the way. For example, now most record players actually convert these vibrations into electric signals that are passed into a speaker system for amplification. This lets the user control more of the details of the sound, such as volume or digital effects. Another advanced trend that has become popular with audiophiles is that of laser reading for records. Just like a laser optical mouse, which uses an infrared laser to detect movement, this device shines a laser at the record and creates the sound signal based off of what data is reflected back to the receiver. The laser is also significant because it can actually read some damaged records, as it is able to register the grooves of the record without making physical contact [3].
Knipsermann/Wikimedi​a
Figure 5: Close-up view of a stylus as it moves across grooves in a record.