The attention wave is a phrase which, as far as I can tell, originated with Daniel Ingram and seems to be something most readily discerned by those who've done noting or vipassana. Tarin Greco calls it a "stir of passions" which may be a bit more of a picturesque and easy to understand name for the same thing. Don't get caught up in trying to figure it out or line up your experience with the description I'm about to give as this is just based on my own experience.
The attention wave itself is the 'bounce' of attention as it flits back of forth between subject and object. Until you've gotten rid of the self-belief entirely there's a sort of triality to the way it moves in that it's continually ricocheting from object to sense door, back through the self-pattern of sensations, and 'round again. You can catch it happening if you try to do something like watch how the attention moves from the front to the back of the head, catching it every time it happens and observing how something kinda flickers between the two. The something that jumps back and forth is the attention wave, it's not hugely complicated but could throw people not familiar with this terminology, which seems to be unique to the pragmatic dharma community.
Hope that helps, and also welcome to the DhO.
