Nothing transforms the landscape quite like a heavy snowfall. The world doesn’t just look different, it sounds different.
We’ve all experienced it. But have you ever wondered why?
Depending on where you are, part of the difference has to do with the way snowy roads can muffle vehicle tires — rather than riding directly on the hard asphalt, tires are riding on a soft pillow of snow. There are also often fewer people on the road during and right after a snowstorm.
In the woods, there’s also less birdsong during a snowstorm as birds hunker down just like people do.
But the biggest cause of snowy silence is the snow itself.
Snowflakes, as we learned in elementary school, are crystals. And while it may not feel like it when you’re shoveling the stuff, snow contains a lot of air in the spaces between those crystals.
Sound travels in waves. When those waves strike hard surfaces like pavement or rocks, they are reflected and even amplified. But when a sound wave encounters a porous, multi-faceted surface, a lot of its energy is absorbed and the sound dies away.
The effect is most noticeable with higher frequency sounds. Lower sounds aren’t absorbed as well by insulating materials — which is the reason you can hear the bass of a stereo through an apartment wall, but not hear the higher sounds.
Because of that, snow doesn’t just muffle sound: it actually changes the soundscape that we’re used to hearing. The lower, deeper sounds still come through, but the upper register of sounds is muffled, creating a charmingly disorienting effect.
How much sound does snow absorb? A lot. Acoustical engineers measure sound absorption on a scale from 0 to 1 – marble is zero, an inch-thick layer of cork is .75, and commercial acoustical tiles are 1, meaning they absorb 100% of the sound energy. Fresh snow can rank from 0.5 to 0.9.
That’s a big range, and it depends partly on the thickness of the snow — more snow means more sound absorption – and on the kind of snow. The fluffy, light snow that we see when the temperatures are a few degrees below zero absorbs more sound than heavy wet snow.
Wet snow contains less air and behaves more like a solid. That’s why the sound muffling effect of snow is only seen when the snow is fresh. As the snow settles, melting and refreezing, it stops absorbing the sound and begins reflecting it. Which explains why your boots can sound so incredibly loud when you’re crunching through older snow.
So the next time it snows, take a moment to step outside and listen, knowing that you’re hearing the world in a completely different way.
*Photo by Green Ant