The antonyms for the word "more sweet sounding" would include terms that describe sounds that are harsh, unpleasant, or discordant. These could include words like grating, jarring, unpleasant, cacophonous, or strident. Other antonyms might include descriptors that indicate a lack of sweetness or melody, such as shrill, screeching, or raucous. Essentially, any word that connotes a sound that is at odds with the idea of sweetness would serve as an antonym to the phrase "more sweet sounding.