Polyphony and monophony in instruments
The term polyphony ( from Ancient Greek πολύ poly 'much', 'more', and φωνή phone " voice ") means in electrical Phonen that a device for generating a plurality simultaneously sounding Direction tones capable (in contrast to monophonic or for unison ). Not only the number of concurrent sounds is paramount to the degree of polyphony, but also their independence, about what envelope ( ADSR ) or timbre concerns. In general, separate musical voices also need separate channels, with stereophonic transmission, two channels per voice. If the tone of the individual voices can be different, it is called multitimbrality.
In music theory, however, is with the term polyphony meant that the simultaneous voices behave as independent as possible to each other without violating common rules ( eg allowing chords ).
Early Electric Phone
The early purely electronic musical instruments such as the theremin, the ondes Martenot since 1919 or since 1928 were monophonic, as they only had a single variable oscillation circuit. The audible frequencies generated by the principle of the beat buzzer. So they could only be used as a melody instrument.
Early electronic organs such as the Hammond organ since 1935, however, produced the sounds over a larger number of mechanical tone wheels that rotated in front of electromagnetic pickups. In this way any number of sounds could be heard at the same time. The early forms of electronic pianos such as the Neo - Bechstein based on mechanical sound production, which was implemented with the help of pickups into electrical signals, and thereby allowed a polyphonic play.
Analog synthesizers
The early synthesizer, however, such as the Moog synthesizer since the 1960s, the sound frequencies generated electronically and were initially limited to a single signal generator. At its heart was a voltage controlled oscillator. The mutability of the then new sound by modulators and filters was held to be more important than a more consistent game.
Roughly speaking, a device needs several separately adjustable oscillators to generate polyphonic sounds. It must be remembered that for more complex voices numerous oscillators may be necessary and for the modulation of the sound frequencies ( low frequency oscillator ) and for noise components ( noise generator ) and also rhythms oscillators are used which do not produce votes in the musical sense. - " Real polyphonic " analog synthesizers such as the Yamaha CS -80 did not appear until the mid- 1970s on the market.
Digitizing
The digitization of sound production by the sampler technology, which prevailed since about 1980 (see eg Fairlight CMI), was limited due to the required computing power again to monophonic reproduction. Only in the 1990s true digital polyphony was possible to the standard personal computer.
In the development of ring tones of mobile phones and video game music, polyphony was regarded as an elementary technical progress. The Commodore 64 home computer was able to produce three independent musical voices already in 1982. During the system speaker of PCs in the 1980s could only be isolated tones of himself, enabled the sound card as an accessory, such as those from AdLib, six simultaneous voices in modest quality, in the 1990s there were with Sound Blaster Creative Labs 32 already and more. Since then, all the music files in MP3 format can be played on mobile phones without generating the individual voices again, the issue of polyphony came into the background.
Digital pianos have since the 2010s up to 256 tone generator that can be activated simultaneously in order to spend the most natural and realistic sound can.
Perception
To what extent are perceived in an overall sound at all different musical voices, is independent of the technical possibilities of music-psychological question. Professional musicians learn the distinction together sounding tones in the subject of ear training. An automatic analysis of two -part harmonies happens for example when tone dialing.