A person who formally examines and verifies financial accounts.
Example:
It seems impossible that so many banks could have gotten themselves into so much trouble in the 1980s if their auditors had been doing their jobs.
We don't normally associate auditors with listening -- looking and adding up numbers seems more their line of work. But auditors do have to listen to people's explanations, and perhaps that is the historical link. Both Latin and some old forms of French had words similar to our auditor which meant "hearer," "judge's assistant," and one who examines accounts." So listening and judging have been intertwined with looking at the books for hundreds of years.