Think about how to blend different sounds and how they work together.
You could take an area such as your sports field and use it as a 'mixing desk': somewhere to place all your sounds in, so they can overlap and blend together.
You could locate different sounds in different parts of the field, and make them switch on when you enter a region, but not switch off!
Or you could set sounds to play endlessly or fade away when they finish, so the users might have to run or play two sounds at once to make sense of your mediascape!