I seem to recall watching cartoons as a kid, probably Bugs Bunny stuff, where he makes a loud noise or a yodel (cause yodeling is funny) and that sound causes an avalanche. Can that really happen? Has it happened before? Or is snow a bit more secure than that?
I can’t say for sure that it’s never happened, but I’d be very skeptical of any claims of such an event. Most avalanches occur because of weather changes, earth movement, or human intervention (in Alaska, the railroad has a howitzer mounted on a flat car to try to create preemptive avalanches). Skiers and snow-machiners have triggered avalanches, but that involves already-unstable cornices and conditions.
I don’t know of any reported instances of this, but if the avalanche condition is high enough (4 to 5) ski resorts often detonate on purpose to avoid uncontrolled avalanches.
And given how easy it is for skiers to break off a floe avalanche just with their body weight, a sound wave in the wrong spot doesn’t sound impossible.
You’d have to look at the Swiss who have a proper Institute for Avalanches. Or ask the Mythbusters to test it.