The Collaborative International Dictionary of English v.0.48:
Grating \Grat"ing\, a. [See Grate to rub harshy.] That grates; making a harsh sound; harsh. -- Grat"ing*ly, adv. [1913 Webster]WordNet (r) 3.0 (2006):
gratingly adv 1: in a harsh and grating manner; "her voice fell gratingly on our ears" [syn: gratingly, raspingly, harshly]