View Full Version : Do compact flourescent lights bother pets?

Stephen Tashiro
12-06-2011, 3:26 PM
Do compact flourescent lights bother pets?

I've discovered that they are an extremely strong source of ultrasonic noise. On a physics website, one poster said they should emit sound at frequencies around 40 Khz. That would be within the range of what a cat or dog could hear. I notice my cat isn't alarmed when I turn on a lamp with a compact flourescent bulb, but she doesn't stay near such a lamp. In Winter she likes to sit under table lamps that have incandescent bulbs. I don't notice her doing the same for flourescents. Is this difference explained only by the heat that an incandescent emits? Or does it also have to do with the sounds?

Nobody replied to my thread on ultrasonic leak detectors, so I made a guess and got a "Marksman Ultrasound Detection Tool". I haven't used it for any serious purpose, but I've listened all sorts of household items. (The tool receives ultrasound and changes it to an audible sound.) Things I expected to be loud in the ultrasound region such as the refrigerator, washing machine, microwave, computer and furnace are fairly quiet. Surprisingly the surface of an LCD monitor emits some moderate ultrasonic noise. The vaccuum cleaner is loud, as I would expect since it involves air whoosing out and in at various places.

The biggest surprise for me is how noisy compact flourescent lights are. The tool detects them as a loud drone It's so loud that you can hold the tool a few feet away from a plaster wall and hear a lamp in the room on the otherside of the wall! I think this is genuine sound, not some side effect of electromagnetic radiation, since I can hold my hand in front of the tool and block the noise. I don't think my hand would block electromagnetic radiation that could pass through a plaster wall.

By contrast, incandescent lamps aren't very noisy.

Mike Henderson
12-06-2011, 3:34 PM
I've had florescent lights for a long time, and pets during the same time. I never noticed any action or activity in the pets that related to the lights. Cats like warm places and incandescent lights put out a lot of heat. Florescent lights, not so much heat. So I can understand why a cat would go to an incandescent light.


Rod Sheridan
12-06-2011, 6:41 PM
My experiences are the same as Mike stated, my cats don't mind the ballasts in the lamps.

Of course my older cat (18) is deaf so she's not the ideal test subject.........LOL

We also have a 5 year old cat and a kitten and they show no interest or aversion to the lamp ballasts....................regards, Rod.

P.S. Wavelengths that short are extremely directional and rapidly absorbed by lampshades, fabric etc......

Stephen Tashiro
12-06-2011, 7:01 PM
I should make it clear that I have not listened to "flourescent lights" , meaning the kind that are a long straight tube. I have listened to "compact flourescent lights", which are about the size of an ordinary lightbulb and have a curly tube.

I, myself, am bothered by the humming from the kind that are a long straight tube - never mind the cats!