During the development of Drift, one element gradually became more important than the others.
Not because it was louder.
Not because it was more complex.
It became important because it provided orientation.
A listener can tolerate a surprising amount of ambiguity when there is at least one recognizable point of reference. A recurring sound becomes less of an instrument and more of a landmark.
The composition changes around it.
The landmark remains.
The listener uses it to navigate.