The Collaborative International Dictionary of English v.0.48:

Hearer \Hear"er\ (h[=e]r"[~e]r), n.
   One who hears; an auditor.
   [1913 Webster]

WordNet (r) 3.0 (2006):

hearer
    n 1: someone who listens attentively [syn: hearer, listener,
         auditor, attender]