"You may continue yodeling"

Brian Krosnick, one of COSI's fantastic outreach education specialists, reached out to me with a mythbuster-style query: a common trope in cartoons and movies is for someone to trigger a deadly avalanche by shouting, or even worse, by just whispering. Just how dangerous is a little yodel-le-he-ho on the mountain slope?

Fortunately for hikers and skiers everywhere, a little yodeling can go a long way with no risk of triggering an avalanche. Snowpacks on mountains are indeed precarious situations, with the tremendous weight of the snow itself balanced only by friction. And once set in motion an entire slab of snow can fracture off and slide down a mountain en masse to wreak havoc.

But sound is actually very weak. Think about it: a lungful of air and a tiny voicebox can fill an entire auditorium with sound. If you drop something on the ground, usually less than 5% of the energy is converted into sound. And so on.

A nice loud yell provides less than one hundredth the energy needed to initiate an avalanche, but that doesn't mean mountain-goers are out of danger. Simply walking or skiing on an insecure snowbank can supply the pressure needed to overwhelm stability and trigger an avalanche. Indeed, somewhere north of 90% of fatal avalanches are caused by the very people who end up dying in them.