How are we going to know what sounds are important before we've even heard those sounds? It's an absurd question. The only thing we can say is that we're going to base it on our past experience. In other words, modern listening doesn't inform us of anything new. It simply keeps us in the past.

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.

The most sensitive frequencies are at the resonant frequencies of the auditory canal. In other words, the ear has shaped itself to naturally amplify certain bandwidth. And that corresponds to sounds in that bandwidth that were most important to our evolving ancestors to hear, in order to survive. And it doesn't match the human voice. It matches birdsong.

"Acoustic ecologist" is basically a fancy name for someone who tries to become a better listener. Not just listening to those thoughts, ideas, and productions of human intention, but listening to places - whether it's an urban environment, residential, industrial, or even the farthest corner of the world, in one of our last great quiet places where we can listen to the pure sounds of nature without any human-caused noise intrusions.

The most important thing for our species is, before it speaks, to listen to its environment. That has a higher priority in any species' survival. We need to be listening to our environment - in other words, restoring the quiet - not just to our natural areas, but also to towns like Portland, Maine.

Healthy areas that are richest in information are those areas in the wild where we can get all the information that's available to us within our human hearing range. The most valuable information throughout human evolution has been faint sounds. We tend to think in our modern world that if it's loud, if it grabs our attention, it's important. We get a lot of that in advertising. But in nature, it's the faintest sound that's important; it has determined, in the past of our ancestors, perhaps, if they will live or die. Faint sounds are the earliest clues of newly arriving information.

We're all born listeners. And as a result of our modern lives, and living in a world that has less meaning than the natural world that we evolved to hear, we learn to think of listening not as taking in all the information with equal value, which is the definition of true listening. In our modern world, we tend to think of listening as focusing our attention on what is important and filtering out everything else.