I like Elliot Carter's Eight Etudes and a Fantasy for Woodwind Quartet, particularly the third and seventh etudes that focus on timbre. Etude 3 (first video, at 2:40) isn't as effective, because I was distracted by the bassoon's movement between notes, though I could still hear the shifts in timbre. But in Etude 7 (second video, at 3:00), with the hairpin dynamics to suddenly bring in or out various sounds on the single note, there was real motion, a journey of emotion.
Penderecki came up with an organized theory of timbre, based on the types of materials used to make the sound. However, this theory could not accommodate wind instruments or voices. Crumb creates some very imaginative timbres, but it isn't the only focus of his compositions.
I want to compose some pieces that attune the ear to very subtle changes in timbre. I was inspired by reading Tim Rutherford Johnson's latest article on NewMusicBox. In it, he describes Kunsu Shim's expanding space in limited time.
In one two-hour performance of the piece, Pisaro reports, it was 20 minutes before he could make out any sound at all; after which his sense of hearing had become so attuned that those sounds that were produced began to take on an extraordinary richness.I want to create that degree of sensitivity, but I don't want to take 20 minutes of the audience's time to do it. My goal is for the listeners to be engaged, not annoyed. Is that asking too much?