Basic forms:
* Audible: Able to be heard
* Auditory: Relating to hearing
* Audience: A group of people listening to something
Derived forms:
* Audiophile: A lover of music, especially high-fidelity sound
* Auditory: Relating to the sense of hearing
* Inaudible: Unable to be heard
* Overaudious: Bold and presumptuous
* Preaudit: To examine financial records before they are formally approved
* Audit: A formal examination of financial records
* Auditor: A person who performs an audit
* Auditory: Relating to hearing
Other related words:
* Audience: A group of people listening to something (though not directly related to "aud", this word comes from the Latin "audire", meaning "to hear").
Let me know if you'd like more examples or want to explore specific variations of these words!