Ultrasound rhymes with:
resound, sound, unsound, abound, aground, around, astound, bound, browned, confound, crowned, downed, drowned, expound, found, frowned, ground, hound, impound, inbound, lb, mound, newfound, pound, profound, propound, rebound, redound, renowned, resound, round, sound, surround, unbound, unsound, unwound, wound