Occasionally my ears ring. The first time I heard that expression I thought it meant you would hear something similar to a small bell repeating – ding, ding, ding. But no, the sound is more a persistent "eeeeeee" noise.
Now there are also machines that do the same thing. Fluorescent lights occasionally sound like that and I once had a defective electric appliance that sang to me intermittently.
But here in Costa Rica, there is a bug that rings in your ears. La chicharra, my neighbor called it. We have about 5 giant floodlights that glare all night long, protecting us from anything that might want to go bump in our night. The first few times I heard la chicharra "sing," I thought one of the lights was about to blow. But yesterday one was on the hillside and I also heard the wind-up. The sound was similar to an off-balance motor trying to gain take-off speed. And then… "wheeeeeeeeeeeee." I realized it had to be a bug and asked my neighbor who happened to be outside.
Her comment was that I should wait until next month, when thousands of them would be "singing" at the same time!
I was reminded of the cicadas in a Texas August – the sound is not the same, as the cicada's tone is much lower, but the insects have a similar fly-like shape and they are both LOUD. The chicharras are bigger, however. MUCH bigger. Apparently they can reach up to two inches or so in length! But with no sting, no bite and no crop damage, they are harmless.
Unless you consider driving everyone mad might be harmful.
Well, it's good for the character.