Note: All photos are by Carmen Braden except where indicated.
4CracksBoom (track below) is from Wool Bay, Great Slave Lake, NWT. Recorder: Zoom H4). Hydrophone: Aquarian H2a. Ice depth: 3.5 feet. Water depth: 50feet approx. Temp: -30C, wind chill -35C. I spliced 4 sounds together, increased the gain by 20dB and applied mild noise reduction since the H4 is quite noisy in quiet moments when phantom power is being applied.
2CracksTHUD (track below). Same specs and processing as 4CracksBoom. Beware – the THUD may be loud! If you listen closely you can hear a digital fuzzy noise every few seconds. Very annoying; perhaps it was caused the phantom power again.
The sound of drilling an ice hole. The hydrophone is in another ice hole approximately 20 feet away at a depth of 10 feet. At first the drilling is smooth, but one point the auger bites into the ice and sticks, and I have to scrape to get going again.
The track below is full of Great Thumps.
My first experience listening to the ice cracking was in Wool Bay on Great Slave Lake. I’m not sure whether it was the -30 temperature, or whether the area was “unstable”, but there was a great deal of activity. Listening to the three tracks below should be with caution – many sounds are very quiet, but some are quite loud and there is no real warning when the loud ones occur. Be careful if you have your speaker or headphones turned up too loud! The big cracks and booms often caused me to think that the ice was going to open up below and swallow me whole; not very likely given the general depth of the lake ice (3 feet). But there is a danger of being on a soft piece of ice where a current may be passing under – people have broken through when moving over these areas of rotten ice when driving, snowmobiling or even walking.
Wool Bay 1
Wool Bay 2
Wool Bay 3
The ice is thick enough by January to drive large trucks on. The ice is not as solid as it seems, and is made of many chunks of ice that are frozen together. This patchwork effect makes the ice bend and move like a wave when heavy vehicles move over it. The ‘wave’ will have a crest that runs in front of the vehicle, and if the vehicle drives too fast, it catches up with the wave and can break through the ice at this pressure point.
I found that the ice did make one or several large cracks before vehicles passed me. Once they had passed, the cracking was quieter and soon disappeared as the ice settled. In the track below, my sister drives our Ford Ranger on the ice road past the ice hole several times. The hole is approximately 500 meters from the ice road. I could not hear the engine at all, and only the tires making contact with the snow made any sound.
In the track below, I walk slowly towards a thin piece of ice and it creaks and bends with my weight until my foot breaks through. I pull it out, and do it again.
In the track below I break through again, and this time I thrash about for a minute simulating the sounds of an actual fall through the ice.
In the track below, I am recording my Jez Riley French hydrophone in the left channel, and the Aquarian in the right channel. The French one is much more sensitive. I left the hydrophones approx. 200m. from shore and went back to the cabin and had some tea. There was no one else on the ice during the recording, so all sounds below are just the ice. It was early in the morning, and I think the change in temperature as the air heated caused the activity.
There is a strange sound, almost like a whale call near the end of this track.
The track below has some great cracklings and splinterings. The sounds have been likened to a dry wooden board being twisted and splintered.
The track below has some excellent long splinterings, almost like something is being dragged across the surface.
The track below has two CRACKS that sound very close. It is hard to get a sense of direction underwater, but it is easy to have a sense of distance when listening to the different cracks.
The track below has a higher frequency schluffing. The varieties in the sounds were amazing!
Here are some notes from the above recording I made during my initial listen:
- Sounds like a whale – zipps and groans for a second
- Like a gunshot
- Like a faraway cannon
- Higher frequency schuuuufsplinter
- Low thud somewhere
- Long splinter
The main obstacles for getting clean recordings of ice cracking are people, dogs and snowmobiles. The track below is a dog approaching from an island about 500 meters away. The sound of any movement on the snow surface is instantly transmitted and amplified through the ice. Even shifting one’s weight while standing will cause a ubiquitous and mainly unwanted scrunching noise.