Digital Sound Recording
Digital sound recording, or digital recording, is a modern method for preserving audio by converting sound signals into binary code, which consists of 0s and 1s. This process involves the use of analog-to-digital converters to translate sound waves into digital signals, allowing for the recording of audio without the degradation commonly associated with analog formats. Early sound recordings relied on analog technology, which captured sound waves through physical processes that could wear down over time, leading to a loss in fidelity.
The transition to digital recording began in the 1960s, with significant advancements leading to the first commercially available digital sound recordings on compact discs (CDs) in 1982. These discs encode sound as microscopic pits, read by lasers, making them more durable than their analog counterparts. Digital audio systems allow for high-quality recordings by sampling sound at a high rate, capturing more detail and reducing background noise through effective filtering.
Although CDs were once the standard for music distribution, the rise of online streaming services in the 2010s and 2020s has transformed how people access music, shifting preferences away from physical media. Overall, digital sound recording offers advantages in sound quality, durability, and ease of distribution, making it a cornerstone of contemporary music production and consumption.
Digital Sound Recording
Digital sound recording, also called digital recording, is a method of preserving sound. Audio signals are translated into pulses, which represent patterns of binary digits. These pulses are recorded as 0s and 1s on a device such as a magnetic tape. Most digital recording systems include converters to translate the audio signal to digital on two channels simultaneously. A digital sound system includes a converter to read the digital information and translate it into an audio signal. This signal can be transmitted through a stereo system's amplifier.
Overview
Early sound recordings stored sound in analog format. Sound waves contain pressure fluctuations, which are represented in analog as voltage fluctuations. A microphone converts the sound waves into electrical energy. This energy creates an electrical current, which corresponds to the sound wave's amplitude—the degree of change—and frequency—the number of cycles per unit of time.
An analog recording may be a magnetic impulse, such as on a tape, or a groove, such as on a record. The impulses and grooves are the manifestation of the sound vibration of an analog wave. Playing these recordings requires physical contact between the player and the storage medium—a needle settling into the groove on a vinyl record, for example. This contact degrades or erodes the analog recording. Through repeated use, the recording develops unwanted noise that interferes with its sound.
Fidelity refers to how closely the recorded signal resembles the original signal. High fidelity recordings closely resemble the original signal. Low-quality recordings are described as low fidelity.
Compact Disc Development
The first digital tape recorder was developed during the 1960s. It was demonstrated in 1967 in Japan. In 1972, the Denon label created the first digitally mastered records—vinyl records containing analog signals made from digital recordings. The first digital sound recordings available commercially were compact discs, or CDs. These were first released in 1982.
To make a CD, music is encoded digitally, which means it is saved as numerical data. An analog-to-digital converter (ADC) interprets the analog wave as a sequence of numbers—binary digits, or 0s and 1s—and then records this sequence on a plastic disc as microscopic pits.
Unlike analog signals, which are continuously variable, digital signals contain multiple levels. The points of a digital signal are finite and defined. As an illustration, a digital signal would look like a bar chart with many points or steps, while an analog signal would be a flowing, curved line containing infinite points.
Instead of using a needle or tape head to play back the sound, a laser scans the CD, reading the pits. A digital-to-analog (DAC) converter translates the binary data and produces it as the correct sound. Digital audio is more durable because the recording will not degrade through use because of friction from the needle or other reading device. It can be recorded in high-quality format—high fidelity—or if sound quality is less important, in a lower quality and smaller file size. A recording has perfect reproduction if every time it is played, it sounds the same. During the 2010s and 2020s, CDs fell out of favor when compared to online music streaming services.
How It Works
Digital recording systems sample sounds. Sampling can be understood by comparing it to a strip of movie film. Many images viewed quickly in sequence produce an image that appears to move. When recording digital audio, the system takes a series of signal pictures. The more completely the binary sequence represents the original sound, the more the digital recording will sound like the original.
The sampling rate refers to how many samples per second are taken. The sound on an ordinary music recording has been sampled more than 44,000 times a second, and high-quality audio may be sampled many more times. Sampling allows the focus of the recording—for example, a singer—to be separated from background noise—distractions such as breathing, shuffling of feet, or the hum of a fluorescent light. Digital recordings are purer because the incidental sounds can be recognized and filtered out.
The sampling error is the difference between the original sound wave and the reproduced wave. One way to improve sound quality and reduce the sampling error is to increase the sampling rate while recording.
A high-quality digital file will contain many more bits, or units of data, than a low-quality file. More bits provide much greater detail. The bit rate is the amount of information played back per second, usually referred to as kilobits per second (Kbps). The average music recording, such as those distributed by streaming services, is 128 Kbps. Some extremely high-quality music tracks can be recorded at up to 320 Kbps.
High-quality digital sound takes up more space than low-quality, smaller files. The larger files contain more information, which allows for much greater, richer detail in playback. These files of information are measured in megabytes (MB). A gigabyte (GB) contains about one thousand MB. As an example, a computer's hard drive storage is measured in GB. It may be able to store several thousand low-quality music files, but only a few hundred high-quality files before the memory is full. It could hold more low-quality files, but they would not sound as good as the high-quality files.
Bibliography
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Brain, Marshall. "How Analog and Digital Recording Works." HowStuffWorks. InfoSpace LLC. Web. 6 Sept. 2015. http://electronics.howstuffworks.com/analog-digital.html. Accessed 26 Nov. 2024.
"What Makes Audio and Music Files So Big?" Fortra, 17 Mar. 2022, www.goanywhere.com/blog/how-big-are-audio-and-music-files#. Accessed 26 Nov. 2024.
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