1) One who gives sound testimony 2) Provider of sound testimony 
• (n.) A witness by means of his ears; one who is within hearing and does hear; a hearer.
An individual who hears an incident occur, especially one who later gives a report on what he heard [blend of ear and eyewitness ]
Ear'wit`ness noun A witness by means of his ears; one who is within hearing and does hear; a hearer. Fuller. 
Someone who heard something but didn't actually see it, and can so testify in court. Compare: eyewitness