The sounds of nature

I just got back from a four day camping trip to Turkey Run State Park in western Indiana. We got to camp just in time to experience the full force of Brood X, the largest infestation of 17-year cicadas in the United States. The cicadas are big and somewhat ugly, but they do not bite and they are very slow. They are also very loud. Every afternoon while my son was napping, I would sit outside, next to the tent, marvelling at how loud the cicadas could be. I found one site that has a recording of Brood V, but this doesn't do justice to the depth and intensity of the sounds we experienced in the woods. This recording also doesn't capture how the cicadas also were phased together, creating waves of sound. Localized areas would subside, and then crescendo together.

What was truly interesting to me was that I never was aware of when the cicadas stopped "singing" for the night. At some point I would realize that I hadn't been hearing them for a while, but I never noticed an ebbing of the sound or the stopping point all together. The latter is not surprising, as all the other sounds of the forest would fill in for the cicadas, preventing a complete silence. But the lack of awareness of the waning of the cicada calls illustrates how durations of time can affect our ability to perceive things. Like getting used to a smell, we can get accustomed to unchanging sounds so that we are no longer aware of the sensation. I wrote a paper on time scales in music that briefly mentions this effect. I think I will have to explore this further.