What is Polychromatic Music? - An introduction with comparison of modern microtonal instruments.
Channel: dolomuse
Date: 2015-10-28

A description of Polychromatic Music as a new genre and musical language by Dolores Catherino. 

An introductory comparison of 21st century electronic instruments (multidimensional polyphonic controllers) including the Tonal Plexus, Roli Seaboard, Continuum Fingerboard, and Microzone U-648, from a microtonal perspective.

The Tonal Plexus and Microzone are multidimensional, polyphonically, at the level of the musical pitch language itself, expanding the chromatic language, exponentially, into a greater pitch-resolution (alphabet) dimension of polychromatic languages. Pitches can be played polyphonically in both the left/right chromatic dimension and the front/back polychromatic (color) dimension. The Microzone has polyphonic touch sensitivity and the Tonal Plexus does not, yet the Tonal Plexus layout allows a pitch programming of up to 211 pitches per octave while the Microzone U648 enables up to 72 pitches per octave. 

The Seaboard and Continuum (and LinnStrument, Eigenharp Alpha) are multidimensional, polyphonically, at the level of tactile expression - touch sensitivity in up/down, left/right, and, except the Seaboard, front/back dimensions. 

The LinnStrument is an amazing first-generation hybrid. Each pad-switch has multidimensional expressivity, and the instrument can be programmed polychromatically. However, one limitation of the design, from a polychromatic perspective, is that the pad-switch layout is isomorphic (same fingering ‘shape’/pattern for every key scale/chord type). While this design feature makes the instrument easier to learn, it becomes limiting with advancing levels of proficiency and pitch resolution. Other leading edge features of the LinnStrument include a rudimentary lighting display and the use of open-source software/firmware!

Hopefully, future musical instruments will be able to bring together these polyphonic pitch-resolution and expressive tactile-resolution dimensions, as well as visual 'feedback' (light/color) dimensions into integrated designs. And, an option for multiple pitch regions per key-switch (i.e. hexagonal key option of 1; 3 - center, top, bottom; or 5 - center, top, bottom, right, left pitch regions). This would allow for more complex pitch layouts with fewer physical key-switches.

Although conventional research estimates our hearing range to be within 20 Hz to 20 KHz, higher resolution audio recording formats/encoders and mic, amplifier, speaker technology, extending upper harmonics content beyond 20 KHz, may enable the perception of new interactive and integrated sonic complexities within our auditory range. These new qualities may be perceived as gestalt (sum greater than the parts), and dynamic (evolving, 'organic'  color/shape changes over space and time) qualities of multidimensional sound. 

These intuitions are the result of musically exploring the implications and interactions of harmonics within complex sounds - 'observation' in an auditory sense. Our current understanding of hearing is fundamentally based on the research of auditory characteristics associated with the perception of sine wave ‘tones’; the sonic rendering of an ideal, smooth and periodic mathematical curve function without harmonics. 

We also have an interesting ambiguity in terminology with regard to the measurement of Hertz. In the field of digital audio, a 96 KHz sampling rate indicates 'samples per second' rather than the conventional meaning of 'vibrations per second'. There is an association in that more samples per second can potentially render better approximations of higher harmonic frequencies. But only if they have been recorded, encoded and transduced at high-resolution (above 20 KHz harmonics) from beginning to end of the signal path. 

This seems to be why hearing tests between digital audio conversion at 48 KHz and 96 KHz sampling rates has been inconclusive - in effect, the only difference is the presentation of twice as many samples per second of the same low-resolution (below 20 KHz harmonics) recording. 

And even if you were now able to achieve full frequency-bandwidth to 20 KHz throughout the sound recording, editing, encoding and playback process, this would only capture up to the 2nd harmonic (1st overtone) of a complex 10KHz sound; or the 4th harmonic of a 5 KHz sound, or the 8th harmonic of a 2.5 KHz sound, etc. 

One example of the audible implications of harmonic interactions occurs with the perception of simple combination tones. Yet, it also seems that combination tones are only surface-level examples of a more comprehensive process and phenomena.

Another bottleneck in the full implementation of a polychromatic music system is our MIDI standard (a foundational communications protocol and digital interface for electronic instruments). MIDI remains a 'gold-standard' and, since its emergence in 1983, remains locked-in to 80's era technology limitations (i.e. 16 channels, 128 note numbers). 

More info at: https://newmusicusa.org/nmbx/polychromatic-music/