How Long Are You Able to Hear This Sound?
Here's a little something to play around with. As a child, I was always fascinated by sounds. I truly believe this is what got me started with radio. I recently came across this interesting video that tests your hearing. It's pretty similar to some of the tests they may perform during hearing testing.
Listen to this video at your discretion, but take a listen and see how long you are able to hear the high-pitched sound. Don't try this at work, and you may not want to try it around your loyal pet dog as they may just want a change of address afterward.
How far how were you able to go? I got to around 14,000 before the sound just faded out on me. This could be something to try with the kids, as well. Again, be very careful as to not be exposed too long, but if you want to keep them busy, well, here you go.