Sound recording and reproduction refers to a mechanical or electrical inscription and a process of sound waves re-creating, comprising sound effects, spoken voice, instrumental music or singing. Sound recording technology may be divided on two major types, which are analog recording and digital recording. Acoustic analog recording is made by means of the application of a microphone diaphragm which indicates atmospheric pressure changes, called acoustic sound waves, and then makes their recordings as a graphic demonstration of a sound wave on a medium (a phonograph). As for magnetic tape recording, the sound waves set up vibrations in the microphone diaphragm. 
Then their conversion into a variable electrical current happens. And in turn an electromagnet converts an electrical current to a variable magnet field. It represents the sound as magnetized zones on a plastic tape coated with a magnetic layer. Analog sound reproduction refers to a reversed process during which a larger loudspeaker diaphragm leads to atmosphere pressure changes creating acoustic sound waves. Also, the sound waves that were formed electronically might be recorded straightforwardly from different devices, comprising a synthesizer or an electric guitar. So, acoustics is not applied during the process of recording.
Digital recording and reproduction means conversion of the analog sound signal received with the help of the microphone to a digital format during the digitization process. This enables to store and transmit sound using a great number of different media. Digital recording may store audio as multitude of binary numbers which represent the audio signal’s samples of amplitude at equal periods of time and at a sample rate that has to assure conveying of all sounds that can be heard. In comparison with analog recordings, digital recordings provide a higher level of quality. This is possible not due the fact that digital recordings have higher fidelity. However this is possible as the digital form enables to minimize the quality losses peculiar to analog recording because of electromagnetic interference and noise in playback. Digital audio signals need reconversion to analog format during the process of playback and before they are sent to the earphones or loudspeakers.
Little history of sound recording
Long time ago, written notation was used to record music. Then a mechanical device was used for this purpose to enable automatic music playing. The automatic music reproduction originated in the IX century. Since that time, music reproduction technologies went through numerous stages of development and totally changed. The first machine used for recording actual sounds at the time when they were passing through the air was called a phonutograph. Thus, Édouard-Léоn Scott de Martinville who was a French inventor took out a patent for this device in 1857. So the very first human voice recordings were made with the help of рhonautograph. The recordings made by means of this device are known as рhonautograms. They are the sheets of paper that have sound-wave-modulated white lines made by a stylus that vibrate. This stylus was notching through a soot coating when the paper was passing under it.
Some information about phonautograph
The initial practical sound recording and reproduction machine is known as the mechanical phonograph cylinder. Thomas Edison developed it in 1877. Soon after this, this development enjoyed a great popularity all over the world. During next twenty years the commercialization of sound recordings contributed to the development of the new global industry. Millions of devices were successfully sold by the early 1900s. The invention of mass-production technologies allowed cylinder recordings to be a main new consumer product in the highly developed countries. This device retained a position of the major consumer format for about thirty years, till 1910.
Phonograph cylinder and Disc phonograph
The further very important technical innovation was a gramophone disc, usually ascribed to Emile Berliner. Its introduction occurred in the US in 1889. In comparison with cylinders, the process of manufacturing, transporting and storing of discs was facilitated. Moreover, one of the advantages of discs was the fact that they were louder. By the end of 1914 the disc became the most widespread recording format that was commercially successful. Edison being the major manufacturer of the cylinders developed the Edison Disc Record trying to sweep market again. The audio disc format was the main medium for making consumer sound recordings and retained this position till the end of the XX century.
Standardized speed was not accepted. However different companies provided discs which played at a variety of speeds. Ultimately, the largest recording companies determined industry standard of about 78 rpm (revolutions per minute). But the real speed varied between the United States and all other countries. The specific speed was 78.26 rpm in the United States and 77.92 rpm in all other countries. This difference in speeds arose because of the difference in cyclic rate of the alternating-current power. The disc format’s nominal speed favoured the appearance of nickname – the “seventy-eight”. Shellack, as well as other materials resembling fragile plastic, was used to make discs. Different materials comprising sapphire, mild steel and thorn are used for making discs for playing with needles. Playing life of discs was limited and depended on how the discs were reproduced.
The very first, completely acoustic ways of recording were known with their confined range of frequencies and sensitivity. It was possible to record notes with medium range frequencies, however it was impossible to record notes with extremely high and extremely low range frequencies. It was very difficult to transfer the musical instruments like the violin to disc.
Columbia Records designed the long-playing 331⁄3 rpm microgroove vinyl record. 1948 was market with its release. While RCA Victor released the short-playing 7-inch 45 rpm microgroove vinyl single. This release happened in 1949. By the end of the 1950s, 78 rpm shellac discs were totally replaced by the 2 new vinyl formats in the United States and highly developed countries. However, it should be noted that there was a range of countries where 78 rpm discs were used till the 1960s. The cost of vinyl exceeded the cost of shellac greatly. But vinyl provided better performance in playback and in stamping. Vinyl discs could be long-lasting if they were played with an excellent diamond stylus incorporated in light pickup on a perfectly modified tonearm. These discs were not noisy if the users cared about the adequate protection from scratches, dust and scuffs. Vinyl records were promoted as those that couldn’t be broken. Of course, they could. But nevertheless, vinyl was much more firm in comparison with shellac. By the way, when shellac discs were just invented they were also treated as those that couldn’t be broken in comparison with wax cylinders.
Electrical sound recording
Another important event in the development of sound recording was the invention of electrical recording. That meant that a microphone was applied for converting the sounds into the electrical signals which were amplified and applied for actuating a recording stylus. This development removed the so called horn sound resonance feature peculiar to the acoustical process and allowed to make more precise recordings by means of enlarging audio range frequencies that can be used. Also, the development enabled to capture sounds that formerly couldn’t be recorded.
Sound recording started as a completely mechanical process. But since the 1920s the situation has changed. At that time the microphones have been actively improving, as well as electronic filters have been developing. 1906 was marked by the invention of the Audion triode vacuum tube. The name of inventor was Lee De Forest. His invention was an electronic valve that had enough capability to substantially amplify poor electrical signals. Improved variations of the tube became the foundation for all electronic sound systems till the commercial release of the very first audio devices based on the use of transistors. This happened in the 1950s.
In the early 1920s, a few independent developers and record companies tried to improve technologies and equipment for electrical recording. However Western Electric, the leading company in the telephone industry, outstripped all of them with its resources and possibilities. The company had the most advanced microphone and the forward-looking test equipment and amplifiers. The company has taken out a patent for an electromagnetic recorder in 1917. And in the early 1920s the company made a decision to further develop electrical sound reproducing and recording. The developers of Western Electric were the first to apply mechanical analogs of electric lines and worked out an advanced rubber line recorder. Soon after this the Columbia Phonograph Company and the Victor Talking Machine Company obtained a license for the system. For the next several years smaller record companies obtained a license or worked out other electrical recording systems.
Some recording formats
Phonofilm, as well as other very first motion picture sound systems, applied optical recording technology in the 1920s. This technology implied the graphical record of the audio signal on photographic film. The amplitude options including the signal were applied for modulating a light resource that was represented onto the moving film via a narrow slit enabling photographing of the signal.
The projection device applied a photoelectric cell and a steady light for converting the variations back into the electrical signals. These signals were amplified and then transmitted to loudspeakers behind the screen. Optical sound was the standard motion picture audio system all over the globe and retained its position till the 1950s substituting magnetic soundtracks. Nowadays, all release prints on 35 mm film comprise analog optical soundtracks, generally stereo with Dolby SR noise decrease. Moreover, a digital soundtrack that was optically recorded in Sony SDDS or Dolby Digital format is probably present. Also, an optically recorded timecode is usually comprised for synchronizing CDROMs that contain a DTS soundtrack.
At that time there were a few other very important innovations comprising the development of the very first practical magnetic sound recording system, or the magnetic wire recorder. Valdemar Poulsen who was a Danish inventor worked out it. These recorders were quite efficient, however the sound quality was bad. That’s why between the First World War and the Second World War magnetic wire recorders were generally applied to record voice and promoted as business dictating devices. Guglielmо Marconi was the first developer who designed a magnetic sound recording system applying steel tape in the 1930s. Because of the use of steel for making the recorders, the recorders were kept in locked rooms for the security reasons, as they could injure technicians. As the high recording speed was demanded, the recorders applied large reels, which were approximately 1 meter in diameter. The thin tape could easily break and often really did this. In 1935 AEG, German company, pioneered with the development of the very first practical tape recorder, called the K1 Magnetophon.
Magnetic tape recording
The tape recorder and magnetic tape were also the important inventions. At the very beginning, the paper-based tapes were applied. However, after a while acetate and polyester backing replaced it. In comparison with polyester, acetate was more fragile and could easily break. German audio developers worked out this technology in the 1930s. It was the foundation for all commercial recordings for thirty years – from the 1950s till the 1980s. The developers also invented the AC biasing technology. This technology substantially refined the tape recordings’ frequency response. John T. Mullin who was an American audio developer improved tape recordings in cooperation with Crosby Enterprises. Their very first recorders relied on the use of German recorders which served as an example. The Ampex company was a pioneer in producing the first commercial tape recorders. This happened in the late 1940s.
Magnetic tape forever changed the recording and radio industries. The use of these recorders enabled recording, re-recording, and erasing sound on the same magnetic tape for a great number of times. Also, the tape enabled to make duplication from tape to tape and save the quality of sound. In addition, it became possible to accurately edit recordings. For this it was necessary to physically cut and rejoin the tape. Soon after this Les Paul, an American musician and developer, worked out the very first multitrack tape recorder. This recorder became a significant stage in the recording industry development. With the help of the tapes it became possible for the first time to use exceptionally electronic instruments for making sound recordings. This fact contributed the challenging sound experiments of famous avant garde composers, comprising Karlheinz Stockhausen, as well as the Musiquе Concrètе school. As a result, excellent pop music recording emerged created by The Beach Boys, The Beatles and Frank Zappa.
The application of the magnetic tapes enabled the radio networks to firstly pre-record numerous program’s sections, comprising advertising, while before just live presentations were permitted. Moreover, this allowed the development and duplication of the entire programs’ recordings which became long lasting, complicated and had high level of fidelity. In addition, the tapes became the instrument of satisfaction of legislative and commercial needs of the regulators and broadcasting companies, because they could implement overall logging of radio broadcasts. Developments, comprising tape echo and multitracks, allowed pre-production of the advertisements and radio programs achieving the top level quality and complicacy which was not formerly possible. Combination of influence of these advanced technologies caused substantial improvements in the programs’ content production style and pacing.
Stereophonic sound and High fidelity
Alan Blumlein developed a method to make a sound of an artist during the film to follow the artist’s movements and speech across the screen in 1931. Soon after this, the developer worked out a stereo disc-cutting head and stereo microphones. He made recording of multiple short films that had stereo soundtracks.
Magnetic tape allowed the invention of the initial practical commercial sound systems which were able to make recordings and reproducing of stereophonic sound with high level of fidelity. For twenty years, from the 1930s till the 1940s, any stereo improvements were impeded because of the synchronization issues. In 1937, Bell Laboratories have made substantial improvements of practical stereo sound. The company made a demonstration of a practical two-channel stereo system. It applied a dual sound track on film. The largest movie studios rapidly worked out three-track and four-track sound systems. In 1938, Judy Garland made the very first stereo sound recording for a commercial movie.
Stereo didn’t acquire popularity as a standard for the commercial music recording system and it was in a professional market in the 1950s. But the situation has changed after the development of the Wеstrex stereo phonograph disc which applied the groove format. In the 1940s, Decca Records introduced Full Frequency Range Recording, or FFRR. It gained popularity as an international standard that raised the quality of recordings on vinyl records.
The large pop releases relied on the use of mono and stereo till the early 1970s. But in the mid 1960s stereo started to enjoy wider popularity and consequently a great number of mono recordings were re-mastered.
From 1950s to 1980s
Magnetic tapes changed the recording industry. Most of commercial recordings were mastered on tape by the late 1950s. The development of the transistor caused the electronics revolution. Among the most significant events that happened at that time was the development of the miniaturized transistor radio that was the very first personal music gadget. It was the main consumer luxury product in the 1960s. The device transformed radio broadcasting changing static group practice for a personal activity.
The next significant development was a small cartridge grounded on the use of the tape systems. The compact cassette was the most widespread system at that time. This system completely replaced the bigger 8-track tape. The compact cassette gained popularity as the main consumer audio format. Then, in the 1970s, the Sony Walkman released the first personal music player and contributed the mass distribution of music recordings. Cassettes ware the really first consumer recording and re-recording mediums that achieved a great success on the market. The gramophone record referred to the pre-recorded playback only mediums, while reel-to-reel audio tape recording magnetic tapes were very complicated for the majority of the consumers and they were not portable.
Ray Dolby developed the Dolby noise reduction system. 1966 was marked with the introduction of this system. David Blackmer developed another system that became the most successful in professional audio. There was also a facilitated variation of the noise reduction system invented by Dolby called Dolby B. This system refined the sound of cassette tape recordings by means of decreasing the recorded hissing sound peculiar to the narrow tape that has been applied. The system also was widely used in movie and recording industries. The use of Dolby B in the compact cassette helped to popularize it. The compact cassettes became commercially successful. They became a domestic recording and playback medium. They were a very significant element of hi-fi market in the 1970s and later. Also, the compact cassettes took an advantage of the improvements in the materials from which the tapes were made. At that time the materials with lower noise and wider frequency responses were developed. Also, the cassettes were grounded on the use of chrome and cobalt oxides, which are the magnetic material. Before this, iron oxide was used most usually.
For more than twenty years the multitrack audio cartridge was very popular among the radio networks. However, in the 1960s Bill Lear invented the pre-recorded 8-track cartridge. It was released as a consumer audio format. Generally, this format was targeted on the automotive market. These systems were known with their usability, efficiency and affordability. They were excellent car hi-fi systems, which guaranteed perfect sound quality that was a distinctive feature for the compact cassettes. From the 1970s till 1980s, the cassette became the main consumer format used in portable audio devices because of quite a small size and substantial durability.
The improvements of multi-channel sound lasted for a great number of years. However, in the early 1970s, Quadraphonic sound was introduced. It applied four tracks, as well as four speakers for creating a 360-degree audio field around a person who listened to it. Quadraphonic sound didn’t become successful in a commercial sense. In part, this happened because of existing of other four-channel sound systems. In general, this happened because of bad quality of the music that was released with its help. Ultimately, it left the market in the late 1970s. But it should be noted that this system was an important stage for further development of domestic Surround Sound systems used in the home theaters. Once the DVD has been introduced, they acquired great popularity.
The development of the transistor that hasn’t required much power and has been of a smaller size allowed to speed up the sales of consumer hi-fi sound systems that had high level of fidelity. This transistor replaced the thermionic valve. In the 1950s the majority of the record companies offered monophonic systems which had quite poor sound quality. But top quality stereophonic sound systems generally were not affordable for the consumers. Then, in the 1960s, the US manufactures released advanced modular hi-fi elements. When combined together, they were the foundation for the development of the home sound system. Japanese electronics companies quickly used these inventions. By the 1980s, large companies, comprising Sony, outstripped smaller companies in the sphere of playback and music recording technologies.
More information about Digital recording
In the early 1980s digital sound recording and compact disc were developed. The CD contributed to further development in the consumer music industry. And by the mid 1990s vinyl records became very popular in the small niche market. But at the beginning the record industry severely restrained the development of digital systems, as the record companies were afraid of wide-scale piracy. The matter is that digital systems enabled to make excellent copies of original recordings. But the record companies accepted the digital systems, however applying different protection systems.
The latest and dramatic innovations have been implemented in digital recording. Multiple compressed and uncompressed digital audio file formats have been developed. They enabled the conversion of the digital data to sound in the real time mode and provided cheap mass storage. This contributed to the development of a new kind of portable digital audio player. Long programs of top quality may be recorded on a single disc because of the availability of the technologies that raise the amount of information that might be stored on a one medium. These technologies comprise HD DVD, Super Audio CD, Blu-ray Disc and DVD-A. It’s possible to quickly download sound files from the Internet, as well as from other resources and easily copy them onto digital audio players and personal computers. Digital audio technology is applied in all cases related to the employment of audio. Up-to-date applications, comprising podcasting and Internet radio, have emerged.
Recently, the television, record and movie industries have been totally changed with the technological innovations in editing and recording. Since magnetic tape recording has been developed, audio editing was put into practice. However, cheap mass storage and digital audio makes possible editing of audio files rapid, simple and not costly by means of the computers’ use. Currently, the recording making process is divided onto three stages. They are tracking, mixing and mastering. Multitrack recording allows capturing signals received from a few microphones. And it has numerous advantages, comprising adding different effects, level balancing, limiting and compressing. It also makes mixing and mastering maximally flexible.
Nowadays, it’s possible to find multiple digital audio recording and processing software functioning on a few operating systems applied for computers. The developers worked out software to satisfy any needs of all users, including amateurs and professionals. This type of software had various demands. Flexibility of playback, as well as precision, are the main demands. Highly-qualitative audio and a wide frequency range do not refer to the main demands.
Copyright law began to regulate the use of sound recordings from 1934. This law extends to MP3s embodying recordings, compact discs, vinyl records, digital audiotapes and tapes.
