Synonyms for Squawker (same or very similar meaning)
WordNet sense 1 (a person given to excessive complaints and crying and whining):
complainer, crybaby, grumbler, moaner, whiner, bellyacher, snivellerWordNet sense 2 (the loudspeaker on an intercom or public address system):
squawk box, intercom speakerFrom the ODE community, based on WordNetadd/edit