by Louise Segreto
Spring brings a welcome explosion of operatic natural sounds. As daylight lengthens and temperatures rise, each day brings new voices from a huge cast of living organisms communicating about the most important things in their lives: feeding, defending territory, reproducing, and avoiding predators. Most of us look forward to hearing the overhead honking of geese, the trilling of red winged blackbirds returning to their wetland marshes and choruses of spring peepers chirping in ephemeral ponds. All these familiar sounds are aural evidence of emerging voices joining the opera that unfolds each spring. However, there is so much more going on in nature than we can ascertain with our naked ears.
Soundscape Ecology is a new field of study that explores the acoustic relationships between living organisms, humans and other sounds of our natural and built environment. It allows us to probe deeper into the deeper complexities of our soundscapes. And, through scientific monitoring, scientists can monitor a place’s natural soundscape to determine a measure of its ecosystem health.
Scientists categorize sound as arising out of 3 sources:
- “Biophony” sounds created by living things;
- “Anthrophony” sounds created by human activity like the sounds of traffic, airplanes and radios; and,
- “Geophony” sounds created by non-living sources like weather, wind and water.
By using scientific methodology and collecting sound recordings from sensitive outdoor microphones, acoustic spectrograms can be evaluated and analyzed. Analysis of acoustic spectrograms can tell us about the well being of vocal individual organisms and the overall quality of biological diversity and ecological community health in an area. Such soundscape methodologies have led to new insights into the complex communications in nature both intra and inter species.
I find it fascinating that there are many sounds occurring around us that we are not biologically capable of hearing. Sound frequency is measured in hertz (hz). A hertz is defined as one wave cycle per second. Human hearing starts at around 20 hz and tops out at about 20,000 hz; with best hearing range between 1,000 -5000 hz the range of human speech. (Perhaps that is why we love to hear ourselves talk!) So, for example, despite all your efforts to learn to listen better, you will still not be able to hear the ultrasonic sounds of bats emitting at about 110,000 hz or the sound of earth worms boring beneath your feet.
But, even though high tech sound monitoring tools are not available for casual naturalists, if you listen more attentively, you can train yourself to hear much more. Unplug from your cell phone and ear-buds and try listening for the more subtle sounds of spring. Some studies claim that you can sharpen your sense of hearing by listening to music, especially alternating genres that are clearly distinct from one another. I find that actively listening can be cultivated by just finding a comfortable “sit spot” which I repeatedly return to at dawn and dusk. My favorite is out front of my house near my bird feeders (with a glass of wine in the evenings!) where I go to sit and listen with my eyes closed for about 10-15 minutes each sit. It is a meditation of sorts, but I promise you that it will put you more in touch with your soundscape.
Izaak Walton would tell us “study to be quiet”. Let’s all commit to listening more carefully this Spring!