Sound recording is the process by which audio information is captured onto a storage medium such as magnetic tape, optical disc, or flash memory. The audio information, if stored onto one of these media, can be used to reproduce the source audio via loudspeaker system (Crystal 1257).
Sound recordings of this sort are omnipresent in the media. Almost no aspect of the internet is uncontaminated by audio, and professional recordings are everywhere in the arts. Indeed, modern sound recordings figure prominently in film, television, radio, podcasting, public speaking, etc.
To successfully participate in today’s complicated web of social networks and internet media, an aptitude for sound production is a prerequisite.
The modern process of capturing audio proceeds as follows:
- Sound waves are converted into electricity using an electronic device known as a transducer (e.g., microphones and pickups).
- The electronic information produced by the transducer is stored onto tape or computer disc.
- The captured information is made audible via playback machines and loudspeakers.
A transducer is an electronic component that turns one form of energy into another. A microphone is one kind of transducer because it turns sound wave energy into electrical energy, and a speaker is the opposite kind of transducer because it turns electrical energy into sound wave energy.
Transducing audio so it can be recorded is how it is done nowadays, but the technology to record audio circumvented the technology to transduce audio.
This means that the first mechanisms used to record, and playback, audio were strictly mechanical devices that were completely divorced from any use of electricity. This is the case even though, the telephone, which used a transducer at the heart of its construction, and hence, used electricity, was developing around the same time.
The mechanical trick of recording sound without the aid of electricity evolved about one-hundred-and-fifty years ago.
The History of the Phonograph
Sound recording devices were developed during the nineteenth century. The initial experiments in the field were done in 1807 by English scientist, Thomas Young, who devised a method for tracing the vibrational patterns of tuning forks (“Phonograph” para 19).
Developments in sound recording then moved to France where a typesetter and inventor named Edouard-Leon Scott de Martinville patented a device called a Phonautograph in 1857. Martinville’s device was only meant to record audio by visual means, however. And it was not meant to reproduce audio in any way.
Next, also in France, was the proposal made to the Academy of Science by poet/scientist, Charles Cross, for a device known as the Paleophone, which was imagined to be able to record and playback sound. However, it never got beyond the concept stage of development (“Phonograph” para 18-20).
The first commercially viable audio recorder and player was the Phonograph, which was invented in 1877 by American entrepreneur, Thomas Edison (“Phonograph” para 1).
In November 1877, several months after filing his patent, Edison walked into the offices of Scientific American (magazine) carrying his invention and, after a few words of introduction, played a record of a voice saying, “Good morning. How do you do? How do you like the phonograph?” Everyone in the office was flabbergasted (“Phonograph” para 22).
Edison’s machine worked as follows: Sound waves, which were collected and focused via horn flare, initiated the sympathetic vibration of a thin, paper membrane (known as a diaphragm), which was affixed with a metal stylus that transferred the vibrational patterns of the diaphragm into soundwave-shaped dents on the tin surface of a rotating cylinder.
If the carved cylinder was traced back over by the stylus, then the dents would shake the diaphragm in a way that recreated the source audio. The phonograph’s horn flare was used to amplify the diaphragm’s vibrations. So, the phonograph’s playback action performed the opposite maneuver of its recording action.
The whole machinery was compelled into motion via hand crank. If the tin cylinder was coated in wax, then some degree of permanence could be established.
Although no immediate practical applications for the device emerged (outside of party tricks), phonograph parlors, in which customers could pay a nickel to hear recorded selections, soon became popular in America. Most cities had such establishments by the mid 1890’s (“Phonograph” para 37).
Radio, which was coming to the fore during the early twentieth century, was a parallel technology to phonography (The New York Times Guide to Essential Knowledge 809).
Both technologies dealt with audio, so both industries had many pieces of equipment in common. For example, the record and radio industries both came to use amplifiers, speakers, microphones, cables, plugs, transducing elements, signal processors, and so on.
Despite their similarities, radio broadcast and sound recordings differ in that radio sounds are transmitted electronically into the skies to be heard once, and recorded sounds are etched into a permanent archive to be stored indefinitely.
Developments in audio recording continued throughout the twentieth century.
The next part of this blog post offers some details about the magnetic format of audio recording, which was the next sound technology to evolve after phonography.
Magnetic tape technology is the primary operating principle used for tape recorders, video tape recorders, and computer tape drives (“Magnetic tape” para 1).
Magnetic recordings are produced by way of electrochemical processes in which a length of plastic tape treated with iron oxide or chromium particles is used to capture the electronic signatures of sound (“Magnetic tape” para 5).
Common formats of audio tape include reel-to-reel tape machines and compact cassette machines (“Magnetic tape” para 8).
Capturing audio by magnetic means came about as follows:
- In 1898, magnetic wire was invented in Denmark under the guise of the Telegraphone, which was a device that recorded audio by magnetizing a wire with an electromagnet hooked up to a transducer. The audio produced by the Telegraphone sounded terrible, however, so the technology floundered. For twenty years, magnetic formats lay dormant. But, beginning in the early 1920’s, films that used magnetized steel tape for their soundtrack began to be produced in Germany.
- In 1935, also in Germany, the Magnetophon, was invented. This machine was a kind of reel-to-reel tape recorder that, instead of using metal tape, used plastic tape coated with ferrous particles as its recording medium. The ferrous particles on the Magnetophon tape were susceptible to rearrangement via magnetism, hence they could be used to record the electrical content of a sound wave that had been converted into electricity via transducer.
The advantage of plastic tape over metal tape, is that plastic tape can be spliced apart and taped together to rearrange and edit the recorded content. Tape is also useful in its ability to be recorded simultaneously with other tapes, thus facilitating the technique of multitracking whereby two, or more, sound sources are recorded separately but played back simultaneously (Manning 13).
Like phonography, tape recordings are analog, hence they employ no computer-based technology in either the capture or the reproduction of sound.
The main technology used by analog gear, and the reason they’re known as analog, is the technology of the transducer, which, as I outlined above, is an electronic device that converts one form of energy into another. The two energy forms—the physical one and the electrical one—are said to be “analogous” to one another or an “analog” of one another.
An analogy is a comparison made between two or more unlike things to identify some manner of similarity. If you think about that definition and about the physical differences and similarities that exist between sound waves and electricity, then the concept of analog may begin to come into focus.
The modern option to analog recording is digital recording. Although the transduction of sound is still carried on by analog means, the capture of that sound is nowadays carried on by digital means. Consequently, magnetic tape used for analog recording is all but obsolete.
Digital recordings are produced by way of sampling and coding. A computer “listens” to transduced sound at exact moments (i.e., many thousands of times per second) and converts each time sample into a numeric code of 1’s and 0’s. The degree to which a computer can discern audio signal over time is described by its sample rate.
The computer reassembles the shape of the sound wave by distributing the numeric information at discrete intervals upon a quantized time map. The degree to which a computer can accurately recreate the source material is described by its bit depth.
For example, a sample rate of 44.1kHz and a bit depth of 16 describes the digital quality of compact discs.
Digital recordings are superior to analog recordings because they do not deteriorate via reproduction or transmission. In fact, nearly all recording done today is one-hundred percent digital. An essential piece of gear for any studio—large or small—is a device called an analog-to-digital converter, which transforms microphone, instrument, and line-level signals into digital audio.
Multitracking, as described above, is today carried on wholly within the realm of computer programs and device applications. This kind of setup is sometimes referred to as a “studio in a box.”
A Brief Overview of the Recording Process
The first step in the music recording process is to use microphones (and other transducers) to convert musical sound vibrations into electricity. Then, amplifiers and mixing consoles are used to augment and balance the electronic audio signal. Next, amplified, and balanced, audio is captured using an analog or digital multitrack recorder. Last, the captured music is finalized as a single audio file or tape track.
To successfully record musical audio, it is best to set up a guide track. Guide tracks can consist of one of the following: (1) click track, (2) drum loop, or (3) scratch track. A guide track is often constructed with drums and bass, which is a combination sometimes referred to as a rhythm track.
After the rhythm track is completed, the next step is to add the harmony, which is the music’s chord sequence. The harmony is usually provided by a guitar, piano, or synthesizer. The next step after adding the harmony is to record the song’s melody, which is the part of the music that you can sing or hum along to. It’s usually provided by vocals and lead instruments. Often, another type of melody, known as a supporting melody is added to the mix. These secondary tunes are typically provided by guitar, keyboards, strings, or background vocals.
Nuance color and flare are added via sound effects, drum fills, hand claps, auxiliary percussion, and many other species of auditory ornament.
After basic tracking is over, the next order of business is to edit the musical content for form and style. This means that all mistakes are removed, the performances are nudged or time-stretched into alignment with the click track, all lead instruments and vocals are tuned or otherwise adjusted for pitch, the arrangement is augmented or otherwise altered, and unwanted noises such as amp hiss and breathing sounds are removed from the tracks.
Signal processing usually comes after editing. This is the step whereby recorded sounds are run through electronic components meant to adjust the sound for volume, pan, dynamics, effects, and equalization. The result of signal processing is a more refined and brilliant character of audio.
The project is finalized when the multitrack recording is reduced to a single track, usually an audio file that’s in stereo. Any further adjustment made to this finalized stereo file is known as mastering.
This blog post covered the definition and history of the audio recording process. The goal of this post was to (1) introduce audio recording as a concept, (2) explain the various audio formats, and (3) introduce the techniques used by audio engineers to record music.
To learn more about this subject, read the materials listed in the Works Cited list.
Crystal, David. The Penguin Concise Encyclopedia. Penguin, 2007.
“Magnetic tape.” Wikipedia: The Free Encyclopedia. Wikimedia Foundation, Inc. Web. 9 Jan. 2017.
Manning, Peter. Electronic and Computer Music. 4th ed. Oxford University Press, 2013.
“Phonograph.” Wikipedia: The Free Encyclopedia. Wikimedia Foundation, Inc. Web. 9 Jan. 2017.
The New York Times Guide to Essential Knowledge: A Desk Reference for the Curious Mind. St. Martin’s Press, 2007.