Voice hearing or "auditory hallucinations" is more common than might be expected, affecting 2-4 per cent of us. It can be experienced as part of a range of mental-health disorders, including schizophrenia, affective psychosis and dissociative conditions. Learning to live with the condition can be challenging; however, "Cognitive Behavioural Therapy" (CBT), on which this authoritative self-help guide is based, has been found to be highly effective.