WordNet (r) 3.0 (2006):

squawker
    n 1: a person given to excessive complaints and crying and
         whining [syn: whiner, complainer, moaner,
         sniveller, crybaby, bellyacher, grumbler,
         squawker]
    2: the loudspeaker on an intercom or public address system [syn:
       squawk box, squawker, intercom speaker]