How our ears screen out sounds so that we can listen selectively only to those sounds we want to hear - like a friend's voice across a noisy room for instance - has been revealed by scientists in Australia. Gary Housley, from the University of New South Wales, has found that the inner ear, known as the cochlea, contains a population of sound-sensitive "hair cells" that communicate with the brain and work like miniature amplifiers to control the sensitivity of the ears to different sound frequencies... Like this podcast? Please help us by supporting the Naked Scientists