HOMEWORK
Go to a park or a garden.
You are to remain stationary, listening (perhaps with your eyes closed) until sounds pass by you in all four directions, one traveling east, one south, one west and one north.
What were the sounds? Of course it does not really matter what they were.
The exercise is one of the concentration, and while you are waiting for the sounds that will release you, you hear myriad of others.
The exercise could be done by a group of people as well as on your own.
R. Murray Schafer