I checked out this book from the library.
It is a terrific read. I read it to the children at the day care and then we decided first to step out of the porch to see what we could hear. Then we walked the perimeter of the playground to listen further. We also took a tablet and pen and wrote down all of the things we could hear in our outside world.
Mainly, we could hear the interstate. It happened to be a particularly loud day for it. But we also heard, as they pointed out, the wind in the trees, feet shuffling, crickets, grass moving, a swing squeaking, laughter, a sea gull and the pond. Not sure how the last two were heard but I wrote it down anyway.
It's nice when you actually sit still and take note to all of the things that can be heard. Things that we hear every day and don't really pay attention. You hear a lot more than you acknowledge most of the time.