Astound rhymes with:
abound, aground, around, 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, ultrasound, unbound, unsound, unwound, wound
Astound sounds like:
accident, accustomed, actinide, actinidia, actmedia, assistant, astounded, auctioned