What happens if you have a door or window open ?

The sound remains when opening and closing the door

Try turning off your laptop?

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Is the sound mostly from inside or outside?
Anything in basement below the door or in floor/attic above the door?

Most sound meters have an omni-directional microphone. You could make a crude directional microphone modification by placing a plastic tube about 12" long slipped over the microphone. It might help to detect the sound source; whether within the wall cavity, inside a hole in wall/door, or reflected from your neighbor's home. Some possible electronic stuff that may emit that frequency: phone or cable service box, electronic door lock, outdoor video, indoor security system, door bell, and light ballast.

Walt

I have turned off all the kids tablets and laptops the sound remains. Thank you for the suggestions.

Outdoor equipment - transformers, cables, phone boxes, etc.?

The sound is most concentrated inside an outside entrance door, which has a closet on one side and a door to the powder room on the other, farther away from the entrance the sound is diminished. In the closet and powder room the noise is diminished. Below the area in my crawl space nothing, above the area a second floor bathroom nothing.

I was using my cell phone I can see what I can do about making it more directional or purchasing a proper sound meter.

The power and cable service box don't seem to be making any noise and are about 10 feet away on the exterior. I don't have an electronic door lock, camera, or electronic security system. My door bell is an 1970-80 wired connection. I disconnected the wires on the outside and inside at the bell, the sound remains. I have a recessed light at the entrance don't believe there was a ballast but I tried turning off the power for at least half an hour which I believe would run out most capacitors and still the sound remains.

Thank you for the suggestions.

7 kHz is getting up there in terms of frequency, it is just 1 octave beneath your upper frequency limit for hearing, and is perceived as a whine. Assuming it isn't an insect's nest the most likely source would be some sort of switching power supply to generate higher voltage from a battery.

https://www.szynalski.com/tone-generator/

Cheers

Greg Locock


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I just saw Greg's posting after looking up an online tone generator.
http://onlinetonegenerator.com/
My suggestion would be to verify the frequency you are hearing matches the one (7 kHz) on your phone's audio analyzer app. In lieu of a directional microphone you could use your body as a shield/barrier (rotate body while holding phone close) to verify that when standing outdoors the sound is from your wall/door and not from an external sound source. There is not many physical sound sources that have not been mentioned or thought about. A toilet tank leak or other valve (water or air) could possible cause a high frequency sound; but 7 kHz is quite high!

Perhaps there is some RF interference affecting your phone. I was testing a ship cargo hatch for leaks with an ultrasound meter and transmitter. I could hear a radio station in the headphones at specific locations on the deck! I also had a situation where my neighbor's ham radio antenna was a source of interference.

Please let us know if you find the noise source and eliminate it.

Walt

Geo-Guy,

What has happened with the noise in the last 5-days?

Walt

Hi Strong I updated the original post with the edit resolution.

the culprit was a small cat toy that squeaks when batted, it was located in the general area but when approached it was not where the sound was strongest.

Quote:

the culprit was a small cat toy that squeaks when batted, it was located in the general area but when approached it was not where the sound was strongest.

As I recall, our brain senses the direction of a sound in part by comparing the phase at each ear (along with comparing the amplitude).

That phase comparison approach doesn't work at frequencies where Lambda / 2 is less than the distance between your ears.

v = 343 m/sec
f = 7000 hz
lambda = v / f= 0.049 m ~ 2 inch
lambda / 2 ~ 1 inch

That may be part of the reason that it was difficult for you to localize the sound.
Of course there may be other reasons like echoes.... or maybe a mischievous cat that was just having fun playing with its human (by waiting for you to go away before batting the toy again)!










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HF directionality is established using the shape of the outer ear and the blocking characteristic of the head.

Cheers

Greg Locock


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The original description of the sound should probably have stated that noise was intermittent and not continuous. It also was not a pure tone or single frequency at 7000 Hz. Here is the culprit making the noise:

https://www.bing.com/videos/search?q=cat+toys+that...

Here is the time wave and spectrum (red is maximum and blue is average):


Everyone feeling bad about not guessing that the noise was from a mouse toy!

Walt

It could have been an Annoy-a-tron.

Hah, you're not the first person to come across annoying noises that had "natural" causes.
https://www.csmonitor.com/1985/0812/ahum.html
http://www.oldsaltblog.com/2013/10/the-hum-heard-r...

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Hi Strong, I viewed your video and that is a similar toy however, when the toy partially depressed in a locked position it emmits a continuous tone. The spectrum plot I was seeing on my phone showed a significant spike upto 50 db and would increase and decrease with distance. The plot I was looking at matched the purple line in the image below. I took the reading a couple different days and it always showed a spike with the peak between 6900 to 7200 on different days.

dang,.. dueling spectra.


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