"Ambient Music must be able to accommodate many levels of listening attention without enforcing one in particular; it must be as ignorable as it is interesting."Brian Eno, Music for Airports liner notes, September 1978
Another way to describe ambient music might be to say that it is music which can be loud enough to be heard if desired, but also quiet enough to become part of the environment; just slightly below the threshold of conscious awareness.

If you look at the piece " Lenticular " which appears on "East Edge of the Milky Way"  it has more form than what I would normally categorize as Ambient in that there are definite melodic lines. (Lenticular is an example of what is sometimes called "lyrical ambient"). But even those melodic lines come in and out of conscious awareness. I was using it while giving a treatment the other day and found that it was an ideal piece to use during healing work as it seemed to lift myself and the patient up euphorically and yet was easy to transition into the uplifted quietness of ones own mind.  In a way ambient music Is a perfect qi moving tool as as it is gently disruptive to repetitive thinking where arising thoughts attract and glue other similar thoughts to one another.

The beauty of ambient music is that it strays from the constant use of one form of hemispheric listening .  In other words many forms of music employ just one form of attention which use the right or left brain only.  When the sound varies from waking state consciousness to slightly deeper consciousness the mind can then employ attraction to either the  left and right hemispheres or in some cases both hemispheres.  I would use the title track "5 Buddhas Full Moon" as an example of this ability to use either or both hemispheres.