So it's not an original topic but it got me thinking about the information content of music. The individual notes are the least part of it. First, there's the intervals - the shift from one note to another. One piece today was 'Indian', and this was signalled by the use of particular intervals we associate with Indian sounds. Second, we have the sequencing of those intervals together. Then there's the silence between the notes; and the rhythms; and the tempos...
But even these things are just really about the notes as written by the composer. The interpretation of the notes is something different, and varies from one occasion to another. There's the relationship between the different performers. Then there's the interpretation given to the music (especially if it's just music without words), which can come through the title of the piece, or the programme notes, or an introduction by the conductor, or by the way the audience experience the piece. And then there's the setting, and the nature of the audience, and even the dress of the performers.
All of these different components (and many others that I've not named) carry information. The significance of each one might vary from one occasion to another, but to me the joy of music is their combination together. You can never step in the same river twice, said Heraclitus. Likewise, you can never listen to the same piece of music twice - even if it's made up of two notes on the recorder.
