6x 30 min interviews (+ 30 min reading time)
Materials given earlier, personal statement, deduction of musical period by ear, sightreading on piano
Read academic literature related to personal statement; don't worry about being challenged or wrong; don't be put off by the weirdness of the texts you might be given; try to improve general knowledge of subject.
Remember this advice isn't official. There is no guarantee it will reflect your experience because university applications can change between years. Check the official Cambridge and Oxford websites for more accurate information on this year's application format and the required tests.
Also, someone else's experience may not reflect your own. Most interviews are more like conversations than tests and like, any conversation, they are quite interactive.
Number of interviews: 6
Skype interview: No
Interview spread: 1 or 2 interviews each day
Length of interviews: 30 minutes each, with 30 minutes to prepare text
I had 6 interviews, including a harmony test, plus an instrumental audition for me. However, most music interviewees only had 3 or 4, including a harmony test (plus an audition).
Before most interviews, there were materials to study (including extracts from music history and musicology texts, musical scores and newspaper articles concerning social issues in music) for half an hour before the interview, then an interview for around 30 minutes which included questions about the texts, such as my opinion on the musicological extracts or when I thought a score had been written.
Other interview questons included examining and asking me to justify the opinions stated in my personal statement, as well as deducing the period, style and purpose of music by ear. The harmony test comprised of sightreading a short, simple piano extract written with one hand in an unusual clef (I was given 5 minutes to practise before performing it) and examining the use of harmony in a short score choral piece (which I was also given 5 minutes to study before questioning).
In preparation, I read academic literature regarding the points I had made in my personal statement (although academic articles online would have made a suitable alternative).
The advice I was given by a teacher at my school who had interviewed himself and just missed out on a place was very useful to keep in mind during interviews: the interviewers will know far more than you about your subject and
This advice kept me calm during interviews, as I was not afraid to be wrong, so long as I demonstrated the ability to learn and construct arguments from the knowledge I did have.
Without going into specifics, the texts to prepare before interviews were often unexpected, sometimes almost absurdly so. Don't let the weirdness of any sources get to you and just form an opinion you can defend on each source.
In retrospect, I would have prepared my general knowledge of my subject (music) better instead of just focusing on reading around the topics I addressed in my personal statement. In my case, this would mean listening to and reading about a wider variety of periods of Western art music (I don't know if this will change each year, but in my interviews the focus was on instrumental music of the Classical period and the mid-late twentieth century).