I’m going to use an answer I read in a book a long, long time ago, that has stuck with me ever since and seems to answer the question rather well:
“Of course there is. There are birds around, aren’t there? And there are always squirrels, or raccoons, or any number of other animals that are quite capable of hearing.”…if you want to make it a truly Zen question, you may assume that there are no organisms anywhere nearby that possess ears to hear, but there are still those organisms that “hear” through vibrations in the air, like bats and many bugs. Imagine a forest completely empty of EVERYTHING but trees, and you’ve lost the realism of the question…
–Do not meddle in the affairs of dragons, for you are crunchy and taste good with ketchup…
Of course it makes a sound. It’s just that nobody is around to hear it. It certainly makes the vibrations and things like that that go into making a sound it’s just that if you don’t hear it…you don’t hear it. It’s like if a tree in China falls right now (and I live in the U.S.) will it make a sound. Of course it will but I won’t hear it.