Out Of Our Hearing

One of the challenges of preaching: The church is a community of people who have lived near a waterfall their whole lives. Allow some patients from a psychiatric ward to explain:

Harding gives him a blank look. 'Exactly what noise is it you're referring to, Mr McMurphy?' 

'That damned radio. Boy. It's been going ever since I come in this morning. And don't come on with some baloney that you didn't hear it.' 

Harding cocks his ear to the ceiling. 'Oh, yes, the so-called music. Yes, I suppose we do hear it if we concentrate, but then one can hear one's own heartbeat too, if he concentrates hard enough.' He grins at McMurphy. 'You see, that's a recording playing up there, my friend. We seldom hear the radio. The world news might not be therapeutic. And we've all heard that recording so many times now it simply slides out of our hearing, the way the sound of a waterfall soon becomes an unheard sound to those who live near it. Do you think if you lived near a waterfall you could hear it very long?'

If a tree falls, and everyone around is so used to it, does it make a sound?