The antonym for the phrase "makes heard" is "muffles." Whereas "makes heard" implies the act of expressing oneself in a way that others can hear and understand, "muffles" denotes the opposite, that is, preventing sound or speech from being heard clearly or at all. Other antonyms for "makes heard" include "silences," "supress," "mutes," and "hushes." These antonyms are often used in contexts where there is deliberate effort to prevent someone or something from making a noise or being heard, such as in libraries, classrooms, or confidential meetings. In summary, the antonyms for "makes heard" all connote a lack of or effort against expression, communication, and sound.