Something special happens when you skip a rock across a frozen lake. That's exactly what Cory Williams in Eagle River, Alaska captured on video for his YouTube channel, DudeLikeHELLA.
As it turns out, we learned that if you stand too close to the thrown rock to where it strikes the ice of a frozen body of water, all you will here is a simple crack. However, if you hurl the stone a fair distance away from you and listen, this is what you will hear. The higher tones arrive first, and you hear a downward chirp.
This is because the ice acts like a vibrating plate. When the stone impacts the ice, a bending or flexural wave is emitted in the ice. The wave travels at supersonic speed, continuously radiating sound into the air while it zips outward, away from the impact. The wave pattern resembles that produced by a pebble dropped in a pond. Because short waves travel faster than long waves, the higher pitches, or frequencies, hit your ear first. Stand too close and you won't hear this split.