Imagine yourself standing atop of Diablo Dam in the early morning of a crisp, winter day. Behind you five ravens are circling near a patch of trees lining Diablo Lake. One of the Seattle City Light boats speeds on in the distance quickly becoming quieter and softer. As you open your mouth to let the cool mountain air fill your lungs time seems to slow. When you finally expel the air out you hear this:
Earlier last week Hannah Newell and I, both students at the North Cascades Institute’s Graduate Program, went atop of Diablo Dam to study how sounds move throughout our mountain corridor. The valley that the Skagit river made over thousands of years is very drastic in our neck of the woods. Toward the mouth of the river the Skagit is met by mostly flat land. As you venture towards the headwaters the surrounding slopes become more and more drastic with hundreds of feet of elevation difference over a very short distance.
This topography makes for extreme echoes when done in the correct spots. Diablo Dam provides the perfect height and distance from each side so that when the sound moves down valley it has the most room to exist. After experimenting at different spots on and around Diablo Lake, I found the middle outcrop of the dam was the perfect spot for echo calling.
As I already described the morning that Hannah and I went to record had the perfect conditions for sound travel. While cold air doesn’t help sound travel farther, a windless day is essential. Air currents can often “muck up” the sound so that you cannot hear the echo as well. The snow on the ground also helped to send the sound back to us even though there was only a small layer of it. When creating your own echoes in the mountains make sure to check with theNorthwest Avalanche Center so that you do not start any unwanted avalanches.
When listening to this at home I highly recommend sitting in a quiet place and putting on headphones. You might need to adjust the volume on your device so that you can hear all of the echoes. Even on the recordings you can hear each echo come back five times! Although it doesn’t come close to the world record of 75 seconds I have never personally heard an echo in a natural place more than two or three times.