"Moment Form" is one of the more interesting musical experiments of the 20th century. It is worth reading the Wikipedia article. The inventor of 'moment form' was Karlheinz Stockhausen whom I had the pleasure of meeting in Salzburg in 1988 when he brought his ensemble to the Salzburg Festival and gave a week of performances of his chamber music. I didn't discuss moment form with him, but rather how he incorporates theatrical elements into his chamber music. Stockhausen distinguishes between different kinds of form: moment form, strictly speaking, is a "mosaic of moments" each moment being a self-contained section. "Moment-forming" is a way of writing music that avoids narrative arc, in which the music, one might say, "lives in the now" and is not directed towards a goal. A different kind of form is what Stockhausen calls 'polyvalent' in which the components of the structure can be ordered in different ways. Others have called this kind of form a 'mobile' as the different elements are in a free relationship. Composers have been using these and related ideas to write music since the late 1950s.
One thing the different approaches have in common is that no two performances can ever be the same. This has appealed to a lot of composers and performers as it seems to free us from the horrible Procrustean bed of recording technology where, as soon as a performance is recorded it becomes frozen for all time--a very unmusical thing!
Let's listen to some examples. Here is the piece that originated moment form, Momente, written in various versions between 1962 and 1969:
Though it may seem as if there is a direction, an overall structure, that is really not how it works. There are different kinds of moments, or modular components, and different performances use different collections of them, in different orderings.
In the 1980s Anthony Genge, a Canadian composer I knew quite well and had worked with on several occasions, gave me the score to a new piece called Night Rain for alto flute and guitar. There were three 'movements'. Each movement was written on a single sheet of score. The alto flute part occupied the top half of the page and the guitar part, the bottom. Each part consisted of a number of measures of music, but each measure was a separate section and the measures could be played in any order. There were no indications of coordination between the flute and guitar. So, a musical mobile or, perhaps also moment form? The flute player that I performed this with, Richard Volet, and I noticed that there were certain recurring elements. For example, one brief melodic cell, three notes rising and falling, occurs a few times in the flute part and also comes in the guitar part. As Richard and I rehearsed the piece together we discovered that the usual issues of ensemble were simply irrelevant. We never needed to coordinate beats or dynamics or phrasing. Each part was independent. We did discover that we needed to know when each movement began and ended. But we developed no obvious signals to coordinate this. We just kept playing the piece and pretty soon we knew what the other player was doing and when the movement was over.
After we had played it for a while and performed it in concert a few times, the composer asked us to record it for him, which we were happy to do. We had gotten pretty good at it and recorded it in a single take, which took both Tony and the recording engineer quite by surprise. They had settled in for a nice long chat in the control room and we were done! Here is that recording with some photos of the west coast of Canada that seemed appropriate:
I have included right after the titles a photo of the composer, Anthony Genge and a photo of myself at the very end, but I was not able to find a photo of Richard Volet. Apologies!