Source : Webster's Revised Unabridged Dictionary (1913)

Grating \Grat"ing\, a. [See {Grate} to rub harshy.]
   That grates; making a harsh sound; harsh. -- {Grat"ing*ly},
   adv.

Source : WordNet®

gratingly
     adv : in a harsh and grating manner; "her voice fell gratingly on
           our ears" [syn: {raspingly}, {harshly}]