the wound landing on a face he never sees
Lenz doesn’t notice the way Green’s face sort of crumples blankly when Lenz mentions the issue of late mothers.
Context
The broadcast is so total it's blind: Lenz jackhammers on "late mothers," the exact wound of Green's own dead mother, and never registers the face crumpling a foot away. The listener is present enough to be hurt and invisible enough that the hurt goes unseen — reception flowing entirely one way while the speaker mistakes an audience for a companion.