My piece Gesleten piano has lamps, tapes and a mirror(and a piano). The theory is easy: Gespleten is a piece with “simple” added objects; everything is full notated on a very clear score. The usage of materials I think it is very organical...
but reality of life is much more complex.
To explain to a performer any extra-musical actions is difficult and demands a lot of the rehearsal time. Usually it is easier with percussion players because they are use to deal with objects (and to carry them!)
So...two points, one from the composer's side, one from the performer.
1. The usage of extra musical resources on the chamber music will improve with the practice (in fact is already improving a lot!), Musicians will be able to do more extra musical things, more and more.
2. but… composers we should think and re-think the usage of each material, every gesture, every "side of the road element". Because any of them in the concrete practice of chamber music (rehearsals, transportation, parafernalia set up, extra explanation to the musicians) is exponential. Any thing we may think is
complicated, will be
very complicated. We can write of course whatever we want. The point is the justification of that.
In the classical world a composer can write a string quartet with only one single note for flute, or a string quartet played on flying helicopters... why not…
but
we composers should be aware of what we are doing, it is part of our task.
Cecilia