When we look at history we generally find it helpful to divide vast expanses of time into eras, these eras are defined by major events such as the K/T boundary with mass extinctions or common trends through out society. In the case of audio development the division of about 125 years become useful because of the vast technological advancements that occurred over a relatively short time.
The last 125 years are commonly divided into 4 eras. These are: The Acoustic Era (1877 to 1925), The Electric Era (1925 to 1945), The Magnetic Era (1945 to 1975) and The Digital Era (1975 to present). In this post we will lightly touch on what makes each era unique.
The first era, The Acoustic Era1 (1877 to 1925), identifies a time when sound recording and playback was done by mechanical means. In other words sound waves interacted with an engraving medium that imprinted onto a media. This media was then able to be played back with a stylus or needle that transformed those engraved grooves into sound waves which could be amplified via cones and horns. This would mean that if you are a performer and wanted to record your performance you would need to perform fairly close to very large metal horns that would focus sound waves to a diaphragm. This vibrating diaphragm would cause a stylus to etch the medium.
Because of the mechanical nature of recording and playback, only certain frequencies would be captured clearly, these were 100 to 2500 Hz. This means that banjo, xylophone, trumpet, trombone, and tenor and baritone voices would be recorded and replayed best. That being said later changes to the technology, such as sharper stylus, softer diaphragm and other improvement helped improve frequency response.2
The second era, The Electric Era1 (1924-1945), was brought on by the wide spread adoption of electricity. The invention of vacuum tubes allowed for electronic amplification and the invention of microphones. Henry Harrison and Joseph Maxfield, both Western Electric engineers lead Bell Labs to develop the first condenser microphone. By attaching the microphone to an electronic amplifier they were able to greatly increase the range of sound frequencies they could record to 50-60000hz. This technology was sold to recording companies and allowed for clearer more realistic sound recording. 3
The third era, The Magnetic Era1 (1945-1975), began with the precursor to what became 8 tracks and then cassettes and then vhs. The astute among you may notice that the start date is the end of WWII, this is not a coincidence. The allies had noticed the Germans recording where of higher quality than what was currently being used by the allies. This was confirmed at the end of the war by the discover of the German invention, Magnetic Tape. The tape was invented in Germany in 1928 by Fritz Pfleumer.
From 1950 on magnetic tape became the standard for audio mastering and because of the high quality led to the invention of the first HIFI stereo. 4
The current era, The Digital Era1 (1975 to present), encompasses much of what we are familiar with in our daily lives. CDs, DVD, Blue Ray, Video Games, MP3, Computers are just some examples of digital media. There are many benefits that come from digital advancements, for examples music editing became easier and easier, to the point were anyone can put together a track or remix on their phone while waiting for dinner to be finished. It also allows for seamless reproduction of master copies, in previous eras the masters would degrade over time, in digital this is not the case.
1: Baker, Dave. “The Lowdown on Recorded Sound Through The Ages.” Recording, Radio Film Connection Blog, 18 Feb. 2019, http://www.rrfedu.com/blog/2018/07/02/history-recorded-sound/#:~:text=When%20thinking%20about%20the%20history,Era%20(1975%20to%20present).
2: “Acoustical Recording : Articles and Essays : National Jukebox : Digital Collections : Library of Congress.” The Library of Congress, http://www.loc.gov/collections/national-jukebox/articles-and-essays/acoustical-recording/#:~:text=In%20sound%20recording%2C%20the%20acoustical,of%20microphones%20or%20electrical%20amplification.
3: “The Electrical Era.” History of Recording, 1 Aug. 2017, historyofrecordingblog.wordpress.com/24-2/.
4: “History of Sound Recording.” Wikipedia, Wikimedia Foundation, 28 Jan. 2021, en.wikipedia.org/wiki/History_of_sound_recording.