Dan Dugan’s Nature Soundscape Lecture (July 18th) was the first time we’ve had a speaker in a couple hours before the talk began to set up. The auditorium was filled with a couple miles of cable, and a loud hissing as — he and a helper calibrated 4 speakers for our listening pleasure. And pleasure it was: a raven quorking its way through redwood trees, rocks crackling, mud bubbling, ice cracking, wind howling through palm trees, frogs croaking, 3 separate flocks of birds successively launching into the air, bats crinkling into the air from lava tubes, and the same bats humming back home later, coyotes singing, Lassen, an overflight of geese wings buzzing, elephant seals grunting and clucking through the sound of surf, the booms of spring ice falls in Yosemite, a chorus of jays in Muir lake, and the sounds of Mariposa Grove.
These were examples of geophony and biophony — sounds of the earth and the biosphere — terms introduced by Mr. Bernie Krause a local soundscape analyst. The importance of soundscape has only come to our attention in the last 25 years and how anthrophony — the sounds that we humans make — can impact ecologies. Our sounds reduce the amount that predators and prey, and mates and friends can hear.
The National Park Service established soundscapes as an official resource in 1999, and have been taking inventories, monitoring changes, and drawing up plans. 6 people in the National Sounds & Night Skies Office in Fort Collins run this effort – lending out gear for parks to monitor their soundscapes.
These monitoring stations produce spectrograms that show sounds over the course of a day. From this all sorts of things can be picked out: bugs, birds, the dawn chorus, and all the anthrophony: mostly aircraft — but you can tell helicopter, from jet, from prop plane. These become important in how Parks then manage overflights from private tourist companies, but also passenger jetways. High altitude jets leave a sound “trail” 30 miles wide. This kind of monitoring has had some impact where in some places aircraft have been limited to certain altitudes, defined lanes, and only certain hours. There has now been discussion of making some parks no-fly zones.
Dan lead us through a lot of the techniques and tools by which his recordings were made. The types of microphones used for different things, the methods of capturing sound: mono, stereo, or surround, how our perception works with these different techniques, and the set up of all those things to effectively catch sound. Delivering these beautiful sounds though doesn’t stop with the recording — which is arduous in itself: hauling in the gear (he has lightweight gear for going further), getting up early to capture the sounds, finding the right place at the right time. It requires a good deal more work in the studio to polish those sounds up and combine recordings. (If you want to know more about this, I recommend signing up with the Nature Sounds Society for more info.)
He led us through a fun exercise looking at a sound spectrogram, and then hearing it — looking for the patterns of all that we were hearing (it was from a rainforest in Costa Rica — so there was a lot going on). The best part of the night was the fruition of all that work — listening with our eyes closed to the beautiful sounds around us.
SF Natural History Series 