Jeannette Nelson - Head of Voice at the National Theatre - shares the voice exercises she uses with many of Britain's leading actors to help to keep their voices in shape.

Whether you perform professionally or you just want to be understood clearly and easily, you can improve your voice by knowing how it works and by practising simple exercises. The aim is not to 'fake it' – to try to sound like someone else. It is to find your authentic voice: to be honestly and clearly you in any situation.