While it still continues an international headhunt for a new leader, it has had to move quickly to fill the job on an interim basis after acting head Royston Gustavson left the position unexpectedly earlier this month.

It is believed Dr Gustavson is on personal leave and will not be returning to the school.

Staff were told on July 12 that Kylie Message, from the ANU's Research School of Humanities and the Arts, would be acting in the role.

But the ANU announced on Monday it had appointed Professor Malcolm Gillies to the position of interim head while it sought a permanent leader.

Professor Gillies, an internationally-renowned music scholar who grew up in Canberra and began at the School of Music as an 11-year-old violin student 50 years ago, said his role as an advisor and mentor would be to ensure a seamless transition process for the school, as it continued its search for a new head.

He said changes and transitions were necessary for universities that wished to remain dynamic, and pointed out several other Australian music institutions were in a similar state of flux.

"This is good, because we want the School of Music to be ahead of knowledge, rather than lagging," he said.

He said that, having served previously as deputy vice-chancellor of the ANU and recently retired as vice-chancellor of the London Metropolitan University, he had no thoughts of putting up his hand for the school's top job.

"My role is a stabilising role and a building role," he said, adding that he wanted to ensure the school was "on the front foot" when it finally did appoint a new head, so it could continue to be a leading institution.

"I've come to a place that's very well set up for that," he said.

Meanwhile, staff and students at the school were perplexed by the sudden movements ahead of next month's final report from the Andrew Podger review.

An ANU spokesman said it would not comment on the circumstances surrounding Dr Gustavson's unexpected departure but that he would be returning to a "substantial leadership role" as Associate Dean (Education) of the College of Arts and Social Sciences after he returned from leave.

ANU Vice-Chancellor Brian Schmidt paid tribute to Dr Gustavson.

"I'd like to thank Royston for his leadership of the School of Music during 2015 and 2016," he said.

"Royston has done a tremendous job to lead the school at a difficult time in its history. He has helped recruit talented new academics to the school, organise the school's academic structures and has reshaped the courses on offer to students."

From October 17, Professor Gillies will be interim head of the School of Music for six months as it enters its next phase with a new permanent head, at which point he will return to a mentoring and advisory role.

The news comes almost a year after former head Peter Tregear left the school, which came three months after the university was embarrassed by the publication of a job ad that appeared to seek his replacement.

The university has struggled to search for a permanent new head, with the leading candidate declining the job earlier this year.

Current and former staff at the school said they were not surprised it was proving difficult to find a new head, given the reputational damage suffered by the school in recent years.

While Professor Schmidt has not denied the deep levels of unhappiness within the school in recent years, he has committed himself to rebuilding the school.

Professor Gillies is the latest in a string of appointments to the School of Music this year, including Dr Christopher Sainsbury, Dr Bonnie McConnell, Dr Natalie Williams and composer Kenneth Lampl, who has moved to Canberra from New York.

Professor Gillies graduated from ANU with a classics degree and then studied music at the University of Cambridge, Kings College London, the University of London and Melbourne University, gaining a higher doctorate in music.

He served as president of the Australian Academy of Humanities and the Council for the Humanities, Arts and Social Sciences.

During his studies, Professor Gillies led the Canberra Youth Orchestra and played with the Canberra Symphony Orchestra.