So indeed listners, I promised you some bonus material. To get you ready for Epsidode 3 this Friday I'm sharing a little spectrograph compliments of bioacoustican, Ashakur Rahaman, at the Cornell Lab of Ornithology. For full disclosure, I participated in the Cornell Lab or Ornithology field recording program in the Sierra Nevadas in June of 2016.
The recording being analyzed here was originally made by Donald K Ljungblad. He recorded the sound near Point Barrow, Alaska. The longer selection of this recording can be found at the Macaulay Library here. So to give a little context, what you are seeing is the recording loaded into a sound analysis program developed by the folks at Cornell called Raven. The bioacousticans can then stretch the sound sample, raise or lower its pitch, or otherwise filter the recording data in order to study what is going on with a particular species' or individual's vocalization. In this sample, you can hear bowhead whales.
As the recording goes along, there is a recurrent higher pitched "blip" running the full length of the y-axis, or frequency representation, of the spectrograph.The x-axis, for this reference, represents time. This means that the "blip" is what is called a full-spectrum event. In other words, that noise contains every individual frequency, or note if you're speaking musically. Since it is equally loud across all frequencies scientists cannot filter the "blip" out of the recordings, or otherwise manipulate it to make it quieter, without impacting their ability to study the whale sounds as those frequencies would also be impacted. Basically, they are stuck with it, as are the whales. The whales are quite unfortunate in that their hearing is far more attuned to low frequencies and all sound, but particularly low sound, travels much farther underwater, especially if this water is cold. So this "blip" amounts to a next door neighbor slamming a door repeatedly, or for those in Portland who live near construction--meaning a fair portion of us--it's basically akin to a pile driver going at all hours.
So what is this "blip" and why is it in the Arctic? That blip is the sound of seismic drilling, which happens every time oil and gas companies explore regions of the Arctic for extraction...regions like the Arctic National Wildlife Refuge, which lies just a little bit east of Point Barrow. However most of the Arctic offshore drilling is happening in the seas on either side of Point Barrow. So imagine how annoyed you get with a construction project next door. Then think of the endangered bowhead whales, who evolved to be in this habitat, use their hearing to navigate under the ice in the dark, their songs to find mates and otherwise communicate, and imagine what you would say to a whale the next time a human says we should keep drilling.
Up next on Threshold Shift, Friday at 10 am, we have ultrasonic sex and death in the Panamanian rainforests...