It's an old Zen koan, something that's meant to clear the mind. If a tree falls in the wood, but no one is around to hear it, does it make a sound? It's a question that's meant to make us think about the difference between the world apart from human perception and the world that our senses actually really create.
Kaspar Henderson's A Book of Noises: Notes on the Auraculous begins with this exact question, something that he says he was asked a lot when he told people he was writing a book about sound and noise. The short answer is yes. That tree will send vibrations through the air, whether or not anyone is listening. And the short answer he says is also no, because sound is an experience. It requires a perceiver to process and understand it. Caspar Henderson coined this term, Auraculous, just for this book. It's a play on words, since miraculous comes from a word meaning to see. Miracles are things we want to see that defy our beliefs.
The auraculus are things that are so beautiful or mysterious we can't believe we are hearing them. And there are many examples in this amazing book of philosophy, science, spirituality, history, and literature. Henderson begins with Cosmophony, the Sounds of Space, covering everything from what Jupiter would sound like to the golden record floating through space on the Voyager. He continues with Giofany, the Sounds of Earth, including a fascinating chapter on the loudest sound in Earth's history, the asteroid strike 66 million years ago in modern day Mexico that wiped out the dinosaurs. The section on biophony examines the sounds of Animal Life, with several chapters on marine life, especially especially whales. Henderson's final section is titled Anthrophony or the Sounds of Humanity.
While the book as a whole moves from the Cosmos to humanity, much like ancient stories of creation, it also moves from the world before and apart from human influence to a world of sound very much illustrative of what some scientists are now calling the Anthropocene. The world is defined by humans. Henderson has a chapter on the Sounds of Hell, both in the religious imagination and the ways in which we humans have created Hells on Earth in sound and Space.
And there is the profound sound of climate change, of glaciers melting, and of the silence of mass extinction events. Henderson ends the book with Silence, which is its own noise. Those who have visited the quietest places on earth, both natural and manmade, report that they hear the sounds of their own bodies hard at work, even the sounds of their body's electrical systems themselves. What What I loved most about this book was the sheer audacity of its combination of so many different forms of knowledge. It's the non-fiction book that really defies categorization. Like an echo, it's the book that will keep making reverberations long after you finish it.