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February 07, 2025, 09:00:26 AM

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Filtering frequency revisited

Started by saturated, January 01, 2025, 10:09:17 PM

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saturated

Hi Mr Joe afaik pretty sure nothing like that existed...however that is an excellent point in that there is or was a plethora of natural gas, propane, pipelines, petroleum in the area. 
I got lucky for some reason I never had to explain to law enforcement why I was sitting in an old heap behind a business by myself at 0200  :tu:

I ask stupid questions
and make stupid mistakes

criticism, critique, derision, flaming, verbal abuse welcome

g1

Quote from: saturated on February 02, 2025, 05:43:03 AMAt night in the small town it got quiet with the exception of an audible hum  :grr
Sometimes I would have the windows open I was in an upstairs room at the end of the house.  This (real or perceived) hum/pitch/monotone frequency tormented me to some end.  In fact I made a few nocturnal excursions around town looking for it.  I would drive around to different areas and shut the engine (slant six 66 Dart) off and sit and try to determine where it was coming from.
Spoiler alert: I never did find it or find out anything.
Tinnitus is not always a ringing and can be a hum.  I have it at 104 Hz.
Most of the time I don't notice, but sometimes it gets bad.

Sometimes the hum can be external though.  For a long time there were people driving around in Windsor, searching for the hum, like you.   :)

https://www.detroitnews.com/story/news/local/wayne-county/2020/07/28/windsor-residents-rejoice-after-mysterious-hum-goes-silent-after-decade/5529975002/

J M Fahey

#17
Interesting data, thanks.

I see a blast furnace as a tube, one end open, one end closed, with high pressure air injected at the closed end: an organ pipe (or a flute)





the analogy is evident.

It will definitely produce sound, at an easy to calculate frequency.

A 20 meter )(60 something feet) long pipe will produce very high power 4.29Hz, go figure.

Chest pounding indeed.

I was *smashed* by the power involved: an Austrian blast furnace used 8.4 MEGA watt blowers, an old 1919 US one used eight 2000kW steam powered ones.

At the same time, the very low frequency/long wavelength (40 meters) makes it very hard for human ears , separated by mere 30 cm/1 ft or so, to pinpoint source.