Between Secrets

Introduction

After recently acquiring a Dave Smith Instruments REV2 16-voice analog synthesizer, I have been very interested in exploring all its possibilities. I was happily surprised to discover that it supports the Midi Tuning Specification standard. This is a standardized set of MIDI messages that allow
to assign any frequency to any midi note. Having never written microtonal music before, I decided to dive in head first and try my hand at writing something.

Microtonal music is one of the least exploited ways to create new music. To the uninitiated it typically conjures images of weird and incomprehensible alien music mostly sounding badly out of tune. While such description no doubt applies to some hardcore experimental compositions, there actually is a whole spectrum of microtonal music possibilities.

People writing microtonal music (even though there are very little to start with) come in a few flavors:

The first kind is looking to create the same kind of music we know from day to day life, but using much purer intervals. Western music in 99.9999% (approximately :) ) of the cases is based on the same 12 notes that evenly divide the octave. This system is known as 12-tone Equal Temperament (also known as 12 tET).

In 12 tET, some note combinations sound smoother together than others. In music terms one speaks of consonance and dissonance. If you analyze these note combinations (or intervals) mathematically,
it turns out that even the consonant ones in fact sound ever so slightly out of tune. Over time, however, our ears have become accustomed to that specific sound. Interestingly, throughout history what is considered to sound "normal" or "good" has changed! By retuning instruments to purer intervals, some consonant chords can be made to sound even more consonant, whereas (as a side effect) some others actually sound worse. There's a whole universe of trade-offs to be made. And a more radical way of working involves retuning instruments on the fly (this is typically only possible with electronic synthesizers) to have the purest possible chords at all times.

A second kind of composers are looking to leave the traditional ways and to exploit new music notes to create new harmonies. This is sometimes called xenharmonic music.

Think about painters: throughout history they've used some types of canvas: in the earliest days there were rocks, later pottery and wood and nowadays the majority of painters has settled on using a canvas made of some kind of paper or fabric. Painting techniques can be adapted to different media: it's a very different experience painting paper than it is to paint rock. Any of these media (rock,wood,pottery,paper,fabric) in principle supports painting any style of painting, although in practice some media seem to be associated to certain styles more than others.

Something similar is true for microtonal music: over time different tuning systems have been popular, but by now the majority in the Western world has settled on 12tET. Nothing prevents us from using other tuning systems, however, and still write medieval, impressionistic, romantic, expressionistic or atonal music in it.

Bohlen-Pierce scale

The Bohlen-Pierce scale divides the "tritave" (= an octave + fifth) in 13 equal steps. I'll spare you the mathematical details. 

In some cases, people have just taken compositions written for 12tET and, after some minor adjustments, replayed them through retuned instruments. Here's an example of Pachelbel's canon in a Bohlen-Pierce scale:

The result still sounds a little alien to me, maybe because the music was originally conceived for the 12tET system and just doesn't fit the new scale

If you change the canvas, you probably ought to invest some time in adapting your painting techniques. Indeed, you read that right: when using a different tuning (e.g. dividing the octave in 13 steps instead of 12), you had better throw out all harmony theory and start with a clean slate.

Some basic principles that span many music theories can still be used to guide music compositions in other tuning systems.

There are the concepts of "consonance" and "dissonance" (because intervals made of notes other than the ones we typically use can still sound consonant or dissonant, in fact even more so!). Consonance and dissonance can be used create tension and release, a tried and proven technique when writing music.

There's the concept of "voice leading" which is fundamental to create smooth sounding chord changes.

It is still possible to use the principles of modulation and cadences to accomplish smooth key changes.

Everything you know about rhythm can be transferred without any change. By trial and error and using your ears carefully you can write music that is adapted to a different tuning, and which still stands a chance of being acceptable to a wider audience.

Of course, since it's using a very different tuning from 12 steps per octave, it will sound a bit different, a bit weird, a bit out of tune but that actually will give the music a new color, a new character, a new appeal. If you have been cursed with absolute hearing basically all hope is lost at this point ;). Note that in addition to using your ears, it also helps to carefully select the instruments that will execute the music. The spectrum of a sound can do a lot for consonance or dissonance. With the right timbres, even in 12tET an octave (=the most consonant interval possible ) can be made to sound very dissonant.

Some people will dislike the new sound, and that's fine too. My own ears, however, have opened a bit, and I will probably try to write more microtonal music in the future.

So without further ado, let's hear my take on some Bohlen-Pierce music: