WordNet (r) 3.0 (2006):

squeaky
    adj 1: having or making a high-pitched sound such as that made
           by a mouse or a rusty hinge [syn: screaky, screechy,
           squeaking, squeaky, squealing]

Moby Thesaurus II by Grady Ward, 1.0:

24 Moby Thesaurus words for "squeaky":
   acute, argute, creaky, ear-piercing, howling, keen, keening,
   penetrating, piercing, piping, reedy, screaky, screeching,
   screechy, sharp, shrieking, shrieky, shrill, squeaking, thin,
   ululant, wailing, whining, whistling