Thanks for creating this new topic (forum anomaly detection…spooky )
Thanks Jos - this is really cool, I can see what you mean, I am really interested to see where this goes as you feed in more information and more layers.
I am thinking this kind of thing must become really complicated very quickly right? Like if you have a large corpus of symbolic data from musical works, how do you manage the similarity between the relationship of a C maj-> C#dim progression in one place and Gmaj -> G#dim in another place?
Some (but not all) of the issues I am struggling with in dealing with this type of data are:
The problem that the human brain can a infer a notion of a tonal centre, and then move this tonal centre to something else (hearing a new key centre as as music modulates), so the semantics of the individual frequencies are affected by the local context of the music and this needs to be accounted for.
The problem of rhythm, not only in that offbeats and onbeats change the sound of how music is heard, but also how time signatures affect music, placing different weightings on certain beats (i.e. the sound of 6/8 time signature is really different from 4/4).
The problem of similarity - for example, having a melodic theme that recurs during a symphony, maybe goes from major to minor, or is augmented in some way, that is still identifiable by the brain but looks like a completely different type of pattern when its converted into data.
I guess all this speaks to the more general question of how on earth do you encode semantics of symbolic music data for nupic type analysis. I would love to hear if people ideas on this.
I saw an interesting paper from ISMIR 2009 at http://ismir2009.ismir.net/proceedings/PS3-7.pdf which people might find interesting.