Vibrato is tension and release. I had an argument with Paul Rolland, who claimed I was rolling above the note and back, but I don't think so. I am in the middle of the note and then releasing'
Cellist János Starker speaks about vibrato in an interview with Paul Katz in 2010. Watch Starker speak about the importance of humility for a successful music career.
Read a tribute to János Starker, who died in April 2013, in The Strad's April 2014 issue - download through The Strad App.