Here at PEBMAC World Headquarters, I play with a lot of electronic toys. Testing new products, playing with gadgets, experimenting with ham radios, and so on. While working on one of these random projects recently, I noticed that my cats got visibly upset when I plugged in a battery charger. The cat was deep asleep, but he immediately woke up, put his ears back, glared at me (and the charger) and left the room. To my ears, the battery charger put off a barely perceptible crackling sound.
Being a gadget nut, I happened to have a device for measuring electromagnetic fields, and it went ballistic next to the charger. This meant that it was quite likely producing sounds at frequencies that were much higher than I could hear, but clearly my cats could.
Curious, I did some research and experimentation. It turns out that lots of home electronics—an ever increasing number, as it turns out*—can produce sounds that are well outside of human hearing range, but within the hearing range of a dog or cat.
Bernie Krause, an environmental sound researcher, has written numerous books and papers showing that man-made sounds can have dramatic affects on animals. A jet plane flying overhead can disrupt the animals in an environment for hours afterwards. Now imagine producing a cacophony of buzzes, squeals, and shrieks, and doing it inside your house at loud volume. It turns out that's what many of us have been doing, but because we can't hear it we don't pay any attention (although recent research shows that we should, since it could very well be making us sick—or worse).
The end result of all of this is that PEBMAC now has specialized equipment that allows us to measure these ultrasonic frequencies. Using it, I can determine which devices are causing these sounds, and how loud they are.
Next time you see me, ask about this service (which I'm now calling SafeInSound), and I'll be happy to provide a demonstration.
* The ban on incandescent bulbs prompted many to switch to LED bulbs. Not only do these bulbs often have a perceptible flicker, but they can also produce a lot of ultrasonic and electromagnetic noise.
Edit: I have changed the name for clarity!