Echo

      Of course, nowadays we don't believe in myths; we explain the voice in the mountains in terms of reflecting sound waves, and we think of this as the sophistication of a now grown-up civilization. This is the way it was explained to me when, as a child, I heard the echo for the first time. I still remember that. I was hammering in the garden outside my house, and heard someone else in the neighborhood also hammering. The funny thing was, whoever it was matched me stroke for stroke. My mother explained to me that it was not someone else hammering at all, but an echo, and she told me about the bouncing sound waves. I remember from then on, every time I did any hammering outside, I enjoyed listening to the sound of my hammer strokes bouncing off the neighbors' windows (why did I assume it was specifically windows?).
      As I grew, I learned about animals who echolocate; and later still, I was intrigued to learn that blind people can also learn to echolocate. So, one day I decided to try echolocation for myself. I was working at a youth camp at that time, and at the end of the muster field was a large dining hall, with two staircases forming wings on the sides; the front of the building thus approximated a parabola. Standing at the far end of the field, I clapped my hands, once, loudly, and heard the echo off the dining hall. I then walked slowly toward the building, making one loud clap every few steps. As I drew nearer and nearer, I noticed that the length of time between the clap and the echo grew shorter and shorter, until, when I stood directly between the wings, there was no echo at all (or rather, the echo was instantaneous and therefore not distinguishable). It was crude compared to the navigational abilities of a bat or a blind person; but with practice I'm sure it could be refined.

      Zion National Park, Utah, U.S.A., is a showcase of canyons, mesas, buttes, all in a glorious desert landscape. One of these features is Refrigerator Canyon, so called because it is always chilly due to it narrowness and east-to-west orientation. Refrigerator Canyon can be a welcome respite from the blazing desert heat; but of at least equal interest is its unusual acoustic properties. I remember hiking down through Refrigerator Canyon, and hearing what sounded like voices inside the opposite wall. It was as if the canyon wall was no more substantial than the wall separating two rooms -- as if there was a room inside the mountain, and I was hearing the voices of people talking inside that room. I knew that could not be; but I could not find an explanation, and the primitive in me was just about ready to believe the impressions of my ears. (Perhaps this is the origin of myths about dwarves and other subterranean peoples.)
      Eventually I found the true explanation of "the room inside the mountain." The voices were those of other hikers higher up the trail; the acoustics of the canyon were such that I could not hear them directly, but only as they reflected off the opposite wall. Nevertheless, Refrigerator Canyon was one of the most memorable and mysterious nature experiences I've ever had.

      I have been describing playing with Echo. But she is by no means good only for play; she has her serious side as well. I can remember many a long month at sea, sitting up cold and sleepy through the watches of the night in the Sonar Control Room, sending out our three-note pulse into the blackness of the ocean and hearing the ghostly wail of the return as it echoed off the seafloor, or the Deep Scattering Layer, or an undersea mountain. I can also remember the nights snug in my bunk, hearing the friendly pulse of the sonar and knowing my shipmates had matters well in hand. I remember the blip on the display screen when the pulse echoed off a submarine during training exercizes -- a lonely ship tracking a still lonelier submarine, in the utter darkness of the nighttime ocean. Echo is not always an oread; she can be a nereid as well