Polyphony and monophony in instruments

Polyphony is a property of musical instruments that means that they can play multiple independent melody lines simultaneously.

An example for monophonic instruments is a trumpet which can generate only one tone (frequency) at a time, except when played by extraordinary musicians.

Duophonic synthesizers, such as the ARP Odyssey and Formanta Polivoks built in the 1970s and 1980s respectively, have a capability to independently play two pitches at a time.

[1] The result is a synthesizer that can play chords, provided all the notes start and end at the same time (homophony).

Harald Bode's Warbo Formant Orguel, developed in 1937, was an archetype of a voice allocation polyphonic synthesizer.

In the early-to-mid-1970s, the voice allocation technology with digital keyboard scanning was independently developed by several engineers and musical instrument manufacturers, including Yamaha,[6] E-mu Systems,[7][8] and Armand Pascetta (Electro Group).

[9][10] The Oberheim Polyphonic Synthesizer[11][12] and Sequential Circuits Prophet-5[13][8] were both developed in collaboration with Dave Rossum of E-mu Systems.

[19] One of the most popular polyphonic synth featuring patch memories, also used E-mu's technology.

To double the polyphony, not only must the number of oscillators be doubled but the electronics must also function as a switch connecting keys to free oscillators instantaneously, implementing an algorithm that decides which notes are turned off if the maximum number of notes is already sounding when an additional key is pressed.

There are several ways to implement this: Modern synthesizers and samplers may use additional, multiple, or user-configurable criteria to decide which notes sound.

The stops or drawbars on the organ modify the signal sent from the audio-generating system, and the keyboard switches the mixer's channels on and off.

Therefore, even though the violin family of instruments are misleadingly considered (when bowing) by general untrained musicians to be primarily monophonic, it can be polyphony by both pizzicato (plucking) and bowing techniques for standard trained soloists and orchestra players.

The evidence can be seen in compositions since the 17th century such as Bach sonatas and partitas for unaccompanied solo violin.

Multiphonics can be used with many regular wind instruments to produce two or more notes at once, although this is considered an extended technique.

Harmonic ocarinas are specifically designed for polyphony, and in these instruments the ranges of the chambers usually overlap to some extent (typically at the unison, third, fourth, fifth, seventh or octave).