Common words:
* audio
* audience
* audit
* auditor
* auditorium
Less common words:
* audacious
* audible
* audibly
* audition
* auditorium
* auditory
* auditioner
Words with specialized meanings:
* audition (the act of listening or hearing)
* auditory (relating to the sense of hearing)
* auditor (a person who examines and verifies accounts)
* audition (a trial performance to assess suitability)
* audit (an official examination of accounts)
Let me know if you'd like more words or a specific type of word!