With the Communicator, if you'd like to allow the audience to leave messages for themselves in a notebook or simply echo back their input in a message stream, you'll need an API trigger to parse the text and a Communicator message to print it.
This is a setup that will work...
API trigger matchphase:
journal_entry && matchphrase |parse('all_chars') as my_journal_entry|
t. [You] |my_journal_entry|