Vibrato, a minute fluctuation of pitch intended to make a musical sound more intense, has shaped – some may say tainted – many genres, from vocal jazz to gospel, Broadway and opera. In light of a current controversial "ban" on vibrato at the BBC Proms, we look at the technique and discuss when, if ever, it's appropriate. Joining us are Mark Katz, a professor of music at the University of North Carolina at Chapel Hill and author of Capturing Sound, and jazz singer and vocal coach Nancy Marano.

Our blog: John Schaefer weighs in on the vibrato debate