i would never claim this stuff is an exact, fully settled science. for example, even though they're friends and on the same "side" in a sense, michel chion objects to bayle's concept of the i-sound:
Representation is more differentiated, sure. But if you listen to capture ephemer again, it sounds more like drum machine pulses and/or proto-glitch towards the end than it does birds flapping their wings.
So this can be relative. I'm not against the concept of representation or images, I just think when we try to talk about sound in a depersonalised sense, we have to talk about its immediately concrete dimensions. The way it envelops the environment, the manner in which it accelerates and decelerates. It's tessitura as you say. Eno's approach I don't find very helpful for this. It's very crude, empiricist late bourgeois gash. Listen! it's a geese honking, as if labour to record that sound can just be subtracted from the process.