You don't really need to engage your visual sense, because the natural wiring of the human psyche is to monitor the environment through sound, not through sight. But we're convinced through modern conditions that we have to look at everything, and that creates stress in our life, because we're trying to solve problems in ways that are much more time consuming, not efficient, and not fun.

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.

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.

I used to hate the urban environment and the urban din. But I realize now that it's really not that much different than living next to a waterfall for wildlife. Most wildlife - unless they're specifically adapted - avoid being around a waterfall or whitewater streams and rivers because it jams their sense of surveillance. They are more vulnerable, and their message loses intelligibility. Now, the ouzel is able to overcome that in various ways. Back to the urban environment, we're talking and delivering messages as if we weren't next to a waterfall, and that's a problem.

Not only does the modern person often think that sight is more important than sound - there's no objective evidence to indicate that. Many people, even audiologists who study the science of human speech and hearing, have assumed for a long time that the human ear evolved to hear the human voice, rather than the voice changing to fit the human ear. And the human ear is actually not a perfect match if we map its sensitivity to the different frequencies in the human range of hearing; it's an unequal curve, it's kind of a wavy line.

What visual information does is it creates priorities. You cannot know with certainty what lies behind something else. There are very few transparent materials in the natural world or the built environment. And so we deal with things superficially, and we deal with what's in front of us, not what's behind our head that we can't see, or to the left or the right. Visualists are often linear and timeline-oriented, whereas the natural condition and the natural way of problem-solving throughout evolution is to be multitasking.

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?