History of sound recording

Experiments in capturing sound on a recording medium for preservation and reproduction began in earnest during the Industrial Revolution of the 1800s. Many pioneering attempts to record and reproduce sound were made during the latter half of the 19th century – notably Scott's Phonautograph of 1857 – and these efforts culminated in the invention of the phonograph, patented by Thomas Edison in 1877.

The history of sound recording - which has progressed in waves, driven by the invention and commercial introduction of new technologies — can be roughly divided into four main periods:

The earliest practical recording technologies were entirely mechanical devices. These recorders typically used a large conical horn to collect and focus the physical air pressure of the sound waves produced by the human voice or musical instruments. A sensitive membrane or diaphragm, located at the apex of the cone, was connected to an articulated scriber or stylus, and as the changing air pressure moved the diaphragm back and forth, the stylus scratched or incised an analogue of the sound waves onto a moving recording medium, such as a roll of coated paper, or a cylinder or disc coated with a soft material such as wax or a soft metal. These early recordings were necessarily of low fidelity and volume, and captured only a narrow segment of the audible sound spectrum — typically only from around 250 Hz up to about 2,500 Hz — so musicians and engineers were forced to adapt to these sonic limitations. Bands of the period often favored louder instruments such as trumpet, cornet and trombone, lower-register brass instruments (such as the tuba and the euphonium) replaced the string bass, and blocks of wood stood in for bass drums; performers also had to arrange themselves strategically around the horn to balance the sound, and to play as loudly as possible. The reproduction of domestic phonographs was similarly limited in both frequency-range and volume — this period gave rise to the expression "put a sock in it", which commemorates the common practice of placing a sock in the horn of the phonograph to muffle the sound for quieter listening. By the end of the acoustic era, the disc had become the standard medium for sound recording, and its dominance in the domestic audio market lasted until the end of the 20th century.

The 'second wave' of sound recording history was ushered in by the introduction of Western Electric's integrated system of electrical microphones, electronic signal amplifiers and electrical disc-cutting machines, which was adopted by major US record labels in 1925. Sound recording now became a process — sound could now be captured, amplified, filtered and balanced electronically, and the disc-cutting head was now electrically-driven, but the actual recording process remained essentially mechanical – the signal was still physically inscribed into a metal or wax 'master' disc, and consumer discs were mass-produced mechanically by stamping an impression of the master disc onto a suitable medium, originally shellac and later polyvinyl plastic. The Westrex system greatly improved the fidelity of sound recording, increasing the reproducible frequency range to a much wider band (between 60 Hz and 6000 Hz) and allowing a new class of professional – the audio engineer – to capture a fuller, richer and more detailed and balanced sound on record, using multiple microphones, connected to multi-channel electronic amplifiers, compressors, filters and sound mixers. Electrical microphones led to a dramatic change in the performance style of singers, ushering in the age of the "Crooner", while electrical amplification had a wide-ranging impact in many areas, enabling the development of broadcast radio, public address systems, and electrically-amplified home gramophones. In addition, the development of electronic amplifiers for musical instruments now enabled quieter instruments such as the guitar and the string bass to compete on equal terms with the naturally louder wind and horn instruments, and musicians and composers also began to experiment with entirely new electronic musical instruments such the Theremin, the Ondes Martenot, the electronic organ, and the Hammond Novachord, the world's first analogue polyphonic synthesiser.

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