It's possible you are thinking of a different object:
* Telescreen: The most prominent listening device in the novel, the Telescreen is a two-way television that constantly broadcasts government propaganda and monitors citizens' conversations and actions.
* The microphones: These are small, hidden devices that can pick up sounds from anywhere in a room. They are particularly prevalent in public spaces and are used to monitor conversations and potentially detect dissent.
* Thought Police: This is a branch of the Party's police force that seeks to prevent any thought or action that could be deemed subversive or disloyal to the Party. They are not a physical device, but rather a constant threat and a force that shapes the citizens' behavior.
If you could provide more context or details about where you encountered the term "ear trumpet" in relation to *1984*, I might be able to help you further.