A sound can be a sound and a sound can be music and the difference is in how we choose to hear it. At least, take that as my working position! Conventional western music organises pitch by dividing an octave into twelve evenly spaced semitones and for the most part, sticking to them like glue. If music is in the hearing of it, then there shouldn't be anything special about these particular notes. Indeed, around the world and over time there are other systems in common use. India and Asia have their own ways of going about stuff, for example. Various experimental systems exist too. Here's something to mess with though - they all tend to be based on a mathematical approach. Take an octave. Think of an integer number. Divide the octave into that many even pieces. Optional: argue about how exactly even the pieces should be. (apologies for my irreverent language to the people doing good work in these fields! :) )
It's temping to believe that a sense of harmony arises from the mathematical relationships between these pitches. People have pointed out that the strongest and most identifiable harmonies have frequencies with a very simple mathematical relationship. It's a big world between the gaps though! The following approach started only with an attempt to study natural sounds that could be perceived 'musically'. Starting with a sample of birdsong, I extracted a selection of pitches by listening carefully and matching them to a frequency generator to find their frequency in Hz. I'm not claiming any scientific rigour here - these are pitches I picked out by ear without worrying too much about it! After a few of these, the 'scale' of notes I was left with was very far from regular. Some notes were very widely spaced, and others much closer than a semitone. The relationships between the frequencies were not at all simple and thus you could easily expect the combinations to be very dissonant!
So on to the listening... The following composition was built from that birdsong scale. The composition also includes other observations such as, when slowed down most of the movement between notes in the birdsong is in fact very fluid. Also, that the sound of the birds is not separate from other ambient sounds in the field recording. Most importantly, to my ear there is something of the nature of the birdsong that is captured and that it is not dissonant. Work on other microtonal scales derived from nature continues... :)