You should expect to be auditioning for our music faculty in a 15-20 minute timeslot. On-campus, you will be auditioning for at least two faculty members in your instrument area, in most cases (e.g. a clarinetist would audition for our Director of Bands and the clarinet professor, and possibly other members of the wind faculty). Some on-campus auditions are recorded, as well.
Expect to be greeted warmly and to have time to perform your prepared pieces in the time provided. Other musical items may be requested (such as scales, sight-reading, tonal memory, etc.). Expect to answer a few interview-style questions about your background and academic interests.
Keep in mind that the music faculty members at your audition have all auditioned themselves and understand how stressful the process can be. They want to hear you at your best, so they all strive to put you at ease and welcome you.