Timeline: Advances in Audio

Key engineering breakthroughs affect how we listen to music

9 August 2017

In celebration of The Institute’s 40th anniversary year, we’re presenting a series of timelines highlighting topics and technologies that have moved forward significantly during the past four decades.

Engineers have been involved in just about every aspect of audio, including recording formats, playback devices, and sound enhancements.

The idea of recording and playing back sound by capturing a magnetic signal on a conductive medium was conceived by American engineer Oberlin Smith in 1888. But it was a Dane, Valdemar Poulsen, who in 1898 built the first working magnetic recorder.

Magnetic recording tape was invented in 1928 by Fritz Pfleumer, a German-Austrian engineer who used oxide bonded to a strip of paper or film. In the 1930s engineers at German companies AEG and BASF perfected the magnetic tape and recorder. Friedrich Matthias with BASF developed a two-layer magnetic tape, bonding a top layer of carbonyl iron powder with a base layer of cellulose acetate. AEG engineer Eduard Schuller in 1933 patented a ring-shaped magnetic head for the recorder. Previous heads were shaped like phonograph needles and damaged the soft tape. Schuller’s ring focused a strong magnetic field on a small area of tape without touching the surface. The system, the Magnetophon K1, debuted in 1935. It was portable and contained its own amplifier and speaker.

Alan Dower Blumlein, a British electrical engineer working for the music recording and publishing company Electric and Musical Industries, filed a patent in 1931 for a two-channel audio system instead of the single, fixed channel used until then. Blumlein called his invention binaural sound, it soon became better known as stereo. In 2015 his breakthrough in sound recording was recognized with an IEEE Milestone.

The Shure Unidyne microphone debuted in 1939 as the world’s first single-element dynamic microphone that offered unidirectionality. A unidirectional microphone is more sensitive to sound coming from the front, and hence relatively unaffected by noise coming from other directions. Still used today, the iconic mic was honored in 2014 with an IEEE Milestone.

In 1954 Regency and Texas Instruments unveiled the TR1, the first commercial transistor pocket radio, which let people on the go listen to music.

Philips introduced the first cassette tape in 1962. Cassettes would dominate the music industry globally for about 10 years until compact discs eclipsed them in 1994.

IEEE members and others have continued to develop formats to enhance the way we enjoy music.

This article was written with assistance from the IEEE History Center, which is partially funded by donations to the IEEE Foundation.

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