If "speaker" refers to the person who speaks:
* Listener: The one who listens to the speaker.
* Audience: A group of people listening to a speaker.
* Hearer: One who perceives sounds, including speech.
If "speaker" refers to the device that produces sound:
* Listener: A device that receives sound, such as headphones.
* Microphone: A device that captures sound, the opposite of a speaker that outputs sound.
* Receiver: A device that receives sound, often in a telephone.
If "speaker" refers to the act of speaking:
* Silence: The absence of sound.
* Writing: Communicating through written text.
* Nonverbal communication: Communicating through gestures, facial expressions, etc.
It's important to consider the specific meaning of "speaker" in the context to determine the most appropriate antonym.