auditor

noun5

1. •
   One who audits bookkeeping accounts.
2. •
   In many jurisdictions, an elected or appointed public official in charge of the public accounts; a comptroller.
3. •
   One who audits an academic course; who attends the lectures but does not earn academic credit.
4. •
   (rare) One who listens, typically as a member of an audience.

   • Thus (as you will see with half an eye, my wise little auditors) these good old dames had fallen into a strange perplexity. — 1851
5. •
   One trained to perform spiritual guidance procedures.