Synonyms for Speaker (same or very similar meaning)
WordNet sense 1 (someone who expresses in language; someone who talks (especially someone who delivers a public speech or someone especially garrulous)):
talker, utterer, verbaliser, verbalizer
WordNet sense 2 (electro-acoustic transducer that converts electrical signals into sounds loud enough to be heard at a distance):
loudspeaker, loudspeaker system, speaker system, speaker unit
From the ODE community, based on WordNet
add/edit