Shrill : (of a voice or sound) high-pitched and piercing.Feeble : lacking physical strength, especially as a result of age or illness.Blunt : (of a cutting implement) not having a sharp edge or point.Muffled : (of a sound) not loud because of being obstructed in some way; muted.Inaudible : unable to be heard.Antonym of Shrill is Muffled