From pages 8-9 of Radio Scriptwriting edited by Sam Boardman-Jacobs:

Nothing is impossible: a lump of rock can philosophise on the ages of man; a child can speak to its mother from the womb; the writer can take the listener to the Battle of Waterloo or to the spaceship Mir without bankrupting the budgets. But, to me, radio’s greatest strength is its ability to creep up on a listener and shake him or her to the core. In a time when we have become anaesthetised by television images of violence, war, deprivation, displacement and famine, radio is, I believe, the most influential and powerful of all the media in that it speaks directly to the individual. It can break down barriers by raising awareness and promoting tolerance and understanding. (In the wrong hands, it can be used to devastating effect.)

Ms. Leicester was speaking about broadcast radio in particular, but other forms of audio delivery — such as podcasts — work similarly.