I did think that I was going crazy, but my daughter, who is totally normal, hears a hum in the master bedroom ceiling also.

No fans in any room are on. Hum is audible with or without AC running.

I checked the frequency of the sound using a tonal tuner on my phone, and it is 120 Hz.

I've read a few articles on the all-knowing interweb, but...

There are no ham radio stations nearby. There is no stereo equipment in the MBR where a bad power supply rectification would produce 120 Hz.

There are fluorescent lights in the attic over the MBR. There are also two attic fans up there. Makes no difference if these are on or off.

It's not loud enough to make me any crazier than I am. I would still like to eliminate this noise.

I had the same thing in my office. It was coming from one of those curly fluorescent lights. Took me months to figure it out especially since it would sometimes stop.

Could happen with a light in a ceiling fan if on a dimmer. 120 Hz is a normal freq for lighting hum,

I'd start by tripping ALL the breakers and see if it goes away.

If it does then turn the breakers back on one at a time untill it comes back, then isolate everything on that circuit.

If it doesn't go away then you know it has an external source. Probably aliens.

Hornet's nest in the attic ?

quote:

Originally posted by SpinZone:
I'd start by tripping ALL the breakers and see if it goes away.

If it does then turn the breakers back on one at a time untill it comes back, then isolate everything on that circuit.

If it doesn't go away then you know it has an external source. Probably aliens.

This ^^^^^

Many moons ago, back when I was doing radio, I had an interference source pop up out of nowhere. At was all across the HF bands. Finally tracked it down to a defective heating pad that had been inadvertently left on. The "pulling the fuses one-by-one" trick was how I finally found it.

quote:

Originally posted by ensigmatic:

quote:

Originally posted by SpinZone:
I'd start by tripping ALL the breakers and see if it goes away.

If it does then turn the breakers back on one at a time untill it comes back, then isolate everything on that circuit.

If it doesn't go away then you know it has an external source. Probably aliens.

This ^^^^^

Many moons ago, back when I was doing radio, I had an interference source pop up out of nowhere. At was all across the HF bands. Finally tracked it down to a defective heating pad that had been inadvertently left on. The "pulling the fuses one-by-one" trick was how I finally found it.

Yep. Isolate the circuit it's on or if it's even electrical. Process of elimination. I like the hornets idea, they man be around 120hz.

Frequency of a bee’s hum

The frequency of the hum that we hear from a bee or any insect is due to the beats of its wings. The sound is actually the result of the bee vibrating its flight muscles, and this can be achieved while the muscles are decoupled from the wings— so they can hum without flying or moving their wings, a feature known in bees but not other insects. This is especially pronounced in bumblebees, as they must warm up their bodies considerably to get airborne at low ambient temperatures.

A bee flying has varying beats but in various studies the figure is about 150 to 200 beats per second or 150 to 200 Hz. This as we can see is well within the acoustic range.

Even in cooler weather or hovering flight rather than flight that moves the bee forward, although the wing beat does change, it is still audible. Wingbeat frequencies for the same breed of honey bee can vary from about 250 Hz down to 190 Hz [see The Journal of Experimental Biology:
"Honeybee flight metabolic rate: does it depend upon air temperature?"] There is also a genetic element "Africanized" honey bees (the so-called "killer bees") tend to have higher wingbeat frequencies in general than European honey bees.

A honey bee in the hive is normally resting and its wing beats are less. A hive is often relatively quiet. The bees are still beating their wings, because honey bees beat their wings to fan the gathered honey and help the water in it to evaporate thus helping it keep. Once the water has gone they then cap the cells with wax. So a bee is always busy and always using its wings, but clearly it uses them less in the hive than outside. On further investigation, however, it appears that when fanning, a bee brings the frequency of its hum down to about 190 Hz. A drone beats its wings at about the same rate.

Bees Healing Bees - Valerie Solheim, Ph.D.

This suggests that 190HZ was the natural frequency level of the hive prior to swarming. Based on the above reference, a probable frequency range appears to be between 150-190Hz. Wenner ‘s sound recordings for the hive come in at 250Hz. Given the variances possible, a sound range between approximately 150-250Hz seems reasonable. I brought my brood hive recording to Professor Chang at the University of Colorado School of Music for an explanation of the sound. Professor Chang determined that the sound was an “E3 about 165 Hz with a variance that goes down a perfect fourth and up around a half step”.

Do you have a dish on your roof, like from dishnet?
I do and I have that hum you are talking about.

It really took me about 6 months to figure out where it was coming from.

I called my provider and they said to call them back if it gets worse???

/\ /\

I would call them back every day and say, "It's getting worse."

I've heard a 120hz hum out of a doorbell transformer that is typically hidden in the attic.

quote:

I've heard a 120hz hum out of a doorbell transformer that is typically hidden in the attic.

Me too! Mine is in the hallway and late at night when the house should be quiet I could hear it. I'm always a little too attentive to noises then , especially running or dripping water.