The electrical era (1925 to 1945) (including sound on film) History of sound recording

ring-and-spring microphones, such western electric microphone, common during electrical age of sound recording c. 1925-1945

the second wave of sound recording history ushered in introduction of western electric s integrated system of electrical microphones, electronic signal amplifiers , electromechanical recorders, adopted major record labels in 1925. sound recording became hybrid process — sound captured, amplified, filtered , balanced electronically, , disc-cutting head electrically powered, actual recording process remained mechanical – signal still physically inscribed wax master disc, , consumer discs mass-produced mechanically stamping metal electroform made wax master suitable substance, shellac-based compound , later polyvinyl plastic. western electric system improved fidelity of sound recording, increasing reproducible frequency range wider band (between 60 hz , 6000 hz) , allowing new class of professional – audio engineer – capture fuller, richer , more detailed , balanced sound on record, using multiple microphones connected multi-channel electronic amplifiers, compressors, filters , mixers. electrical microphones led dramatic change in performance style of singers, ushering in age of crooner , while electronic amplification had wide-ranging impact in many areas, enabling development of broadcast radio, public address systems, , electronically-amplified home record players. in addition, development of electronic amplifiers musical instruments enabled quieter instruments such guitar , string bass compete on equal terms naturally louder wind , horn instruments, , musicians , composers began experiment entirely new electronic musical instruments such theremin, ondes martenot, electronic organ, , hammond novachord, world s first analogue polyphonic synthesiser.

contemporaneous these developments, several inventors engaged in race develop practical methods of providing synchronised sound films. sound films — such landmark 1927 film jazz singer – used large soundtrack records played on turntable mechanically interlocked projector. 1930s movie industry had universally adopted sound-on-film technology, in audio signal recorded used modulate light source imaged onto moving film through narrow slit, allowing photographed variations in density or width of sound track running along dedicated area of film. projector used steady light , photoelectric cell convert variations electrical signal, amplified , sent loudspeakers behind screen. adoption of sound-on-film helped movie-industry audio engineers make rapid advances in process know multi-tracking , multiple separately-recorded audio sources (such voices, sound effects , background music) can replayed simultaneously, mixed together, , synchronised action on film create new blended audio tracks of great sophistication , complexity. 1 of best-known examples of constructed composite sound era famous tarzan yell created series of tarzan movies starring johnny weissmuller.

among vast , rapid changes have taken place on last century of audio recording, notable there 1 crucial audio device, invented @ start of electrical era , has survived virtually unchanged since introduction in 1920s: electro-acoustic transducer, or loudspeaker. common form dynamic loudspeaker – dynamic microphone in reverse. device typically consists of shallow conical diaphragm, of stiff paper-like material concentrically pleated make more flexible, firmly fastened @ perimeter, coil of moving-coil electromagnetic driver attached around apex. when audio signal recording, microphone, or electrified instrument fed through amplifier loudspeaker, varying electromagnetic field created in coil causes , attached cone move backward , forward, , movement generates audio-frequency pressure waves travel through air our ears, hear them sound. although there have been numerous refinements technology, , other related technologies have been introduced (e.g. electrostatic loudspeaker), basic design , function of dynamic loudspeaker has not changed substantially in 90 years, , remains overwhelmingly common, sonically accurate , reliable means of converting electronic audio signals audible sound.