Polyphony (electrophone)
The term polyphony (from ancient Greek πολύ poly "a lot", "more", and φωνή phone "voice") means in electrical Phonen , (in contrast to that a device is capable of generating several simultaneously sounding Direction sounds monophonic or for unison ). Not only the number of simultaneous notes is decisive for the degree of polyphony, but also its independence, for example with regard to the envelope ( ADSR ) or timbre . As a rule, separate musical voices also require separate channels , with stereophonic transmission two channels per voice. If the timbres of the individual voices can be different, one speaks of multitimbrality .
In music theory, on the other hand, the expression polyphony means that the simultaneous voices behave as independently of one another as possible, without violating common rules (e.g. permitted harmonies).
Early electrophones
The early purely electronic musical instruments such as the Theremin since 1919 or the Ondes Martenot since 1928 were monophonic because they only had a single variable oscillating circuit . The audible frequencies were generated according to the beat buzzer principle . So they could only be used as a melody instrument .
In contrast, early electronic organs such as the Hammond organ since 1935 generated the tones via a large number of mechanical tone wheels that rotated in front of electromagnetic pickups . In this way, any number of tones could sound at the same time. The early forms of the electronic piano such as the Neo-Bechstein were based on mechanical sound generation, which was converted into electrical signals with the help of pickups, and thus allowed polyphonic play.
Analog synthesizers
The early synthesizers, on the other hand, such as the Moog synthesizers since the 1960s, generated the sound frequencies electronically and were initially limited to a single signal generator . Its core was a voltage controlled oscillator . The changeability of the then new sound through modulators and filters was considered to be more important than a polyphonic game.
Roughly speaking, a device needs several separately adjustable oscillators to produce polyphonic sounds. It must be taken into account that numerous oscillators may be required for more complex voices and that oscillators that do not generate voices in the musical sense are also used for modulating the sound frequencies ( low frequency oscillator ) and for noise components ( noise generator ) and rhythms . - “Genuinely polyphonic” analog synthesizers like the Yamaha CS-80 did not appear on the market until the mid-1970s.
digitalization
The digitization of sound generation with sampler technology, which became popular around 1980 (see for example Fairlight CMI ), was again limited to monophonic playback because of the computing power required . Real digital polyphony was only possible on commercially available personal computers in the 1990s.
In the development of mobile phone ringtones and video game music , polyphony was seen as a fundamental technological advance. The home computer Commodore 64 was able to produce three independent musical voices in 1982. While the system loudspeaker of the PCs could only emit single tones in the 1980s, the sound cards as accessories, such as those from AdLib , enabled six simultaneous voices in modest quality.In the 1990s, with Sound Blaster from Creative Labs, there were already 32 and more . Since entire music files can be played in MP3 format with mobile phones without generating the individual voices, the question of polyphony has taken a back seat.
Since the 2010s, digital pianos have had up to 256 sound generators that can be controlled simultaneously in order to be able to output a sound that is as natural and realistic as possible.
perception
The extent to which different musical voices are perceived in an overall sound is a question of music psychology and independent of the technical possibilities. Professional musicians learn to distinguish between tones in the subject of ear training . An automatic analysis of two-part sounds is done, for example, with the multi-frequency selection process .
literature
- Gunnar Eisenberg: Identification and classification of musical instrument sounds in monophonic and polyphonic music. Cuvillier, Göttingen 2008, ISBN 978-3-86727-825-6 (also: Berlin, Technical University, dissertation, 2008).