Whenever you're in a natural system and you're making sound, you are putting yourself at risk. As you go up the evolutionary ladder, from insects to frogs to birds and on up into mammals, the higher intelligence recognizes that when you vocalize, you put yourself at risk. So mammals generally vocalize or make noise much more rarely than, let's say, insects or frogs. And when they do, and put themselves at risk, it has to be worth the risk, and have true meaning, such as signaling during a hunting party, calling in prey, some religious or spiritual ceremony, something like that.

You can listen to a birdsong, and from the content of the birdsong, you will be able to determine whether or not the bird grew up in a noise-polluted environment or whether it grew up in a pristine, clean environment. Isn't that incredible?

Acoustic ecology is the study of information systems: the shared acoustic environment and how species send and receive messages in this shared acoustic environment. What these messages mean - meaning, what are the consequences and the changes of behavior in any species. And it has as much to do with us individually and biologically as it does with the shaping of cultures and beliefs.

Most people think visual information is more important than aural information - like, what's this big deal about sound? And why should I bother to listen, rather than look? And here are the facts: there are blind species, in the backs of the caves, the bottoms of the oceans. It's not essential on planet Earth to be able to see, to be a species. But there are no deaf animal species. You have to be able to hear, or you won't get the information you need in order to survive.

If you're going to listen, you have to be willing to be changed by what you've heard. My life has gone through so many changes. I'm sixty-two years old right now, and I'm as busy changing now as I was when I was a teenager, or in my twenties. Every day is different. Every day brings new information.

If you're tired of getting additional information, you can just close your eyes, get some sleep. But earlids, covering of the ears, never evolved. Not once do we find it, even in the fossil records. Because while we let our eyes relax, our ears are still hearing. And that's why alarm clocks work and wake us up. We still gather information. Every animal is gathering information 24/7. So I like to think of acoustic ecologists as people who are trying to become better listeners, 24/7.

I'm in love with Earth. I truly am. And so listening is not work, to work toward a better future. It's joy. To not be able to work toward a better future would be work. That would be tough.