Based on sound:
* Whisper: A very quiet, soft sound.
* Mutter: To speak in a low, unclear voice, often in a way that is hard to hear.
* Speak: To use words to communicate, implying a more formal or individual manner than a chant.
* Sing: To produce musical tones with the voice, implying a more melodic and structured sound.
* Recite: To say something aloud from memory, implying a more formal delivery than a chant.
Based on meaning:
* Silence: The absence of sound.
* Quiet: A state of being peaceful and without noise.
* Disagreement: The opposite of a shared or unified message.
* Individual expression: The expression of personal thoughts and feelings, rather than a collective message.
* Dissonance: A lack of harmony or agreement, the opposite of the unified sound of a chant.
The best antonym will depend on the specific context in which you are using the word "chant."