Presented by Sara Mohr-Pietsch. As Thomas Ades' opera The Exterminating Angel opens for its UK premiere at the Royal Opera House, Sara meets its director Tom Cairns. He reveals just how intense the rehearsal process has been for an opera with a uniquely starry ensemble cast, which includes Anne Sofie von Otter, Christine Rice, John Tomlinson, Thomas Allen, Iestyn Davies and more. Cairns also explains why he finds endings so difficult. As part of the BBC's Minds Matter season, Sara looks at some of the latest research into music therapy for mental health, as therapists Kate Jones and Catherine Carr share their findings from research into children with selective mutism and on acute psychiatric wards. Sara also talks to Grace Watts from the British Association of Music Therapists, and visits a long-running community music project by the mental health charity SMART, meeting its current leader Sarah Wilson and founder Gary Ansdell, who reveals his findings from 10 years of research into the project's impact on patients in recovery. Musician and teacher Adam Ockelford explains his theory for how music works, based on his experience over 40 years working with children who are partially sighted and on the autism spectrum, which is the subject of his new book, Comparing Notes: How we make sense of music. Plus, opera singers Renee Fleming and Angel Blue on the unique voice of Ella Fitzgerald, in the week of centenary celebrations for the American jazz singer.