On a recent Saturday morning I stepped outside to do the usual chores: put yesterday’s recycling in the barrel, take yesterday’s kitchen scraps to the compost pile, fill the bird feeders, and bring in the newspaper. What was unusual was that I was listening to a podcast. The podcast was one that I had downloaded some months ago from On Being. Krista Tippett was interviewing Gordon Hempton, an acoustical ecologist, on the subject of silence.
The interview was interspersed with recordings of sounds that Gordon Hempton would have recorded in his search for The Last Quiet Places: ocean waves, wind blowing in the trees, and bird songs. Although it’s clear that some of the recordings were made by Gordon Hempton, I’m not sure if they all were.
As I stepped through the door into the backyard a recording of a songbird, perhaps a wood sparrow, was being played on the podcast. At the very same moment, in the background and over the sound that was coming through the earbuds, I heard the distinct call of a red-bellied woodpecker in a nearby tree. Maybe it’s because bird songs are sounds that I want to hear that I hear them readily, but near the end of the podcast Gordon Hempton made an observation that human hearing has evolved so that it hears most distinctly sounds in the range of 2.5 to 5 kHz. He points out that this is above the frequency range of most human speech. However, it is the exact frequency of bird song. His conclusion is that “bird song is the primary indicator of habitats prosperous to humans.”
What does this connection between the bird song and human survival mean? Does it mean that if birds are thriving in a given environment, humans will also? Does it imply the obverse, that if birds are threatened by conditions in the environment then humans are as well? This requires more thought. Anyone reading this is invited to comment.