A child's speech depends on their hearing and carers should be on the look-out for problems, says Maggie Jones Since it became known that babies can hear in the womb, expectant couples have sometimes been caught playing Mozart, jazz or other  favourite music to their eagerly anticipated unborn. After birth, babies are able to recognise their mother's voice. From then on the ability to hear is vital for a child to imitate the sounds of speech and develop language. Unfortunately, however,...