Power sub station and me

Crossposting to alt.engineering.electrical. Your entire original message is included below.

The hum is audio noise and not an electric, magnetic, or electromagnetic field (EMF).

----- Original Message ----- From: "Mirth" Newsgroups: sci.physics.electromag Sent: Tuesday, May 10, 2005 9:59 PM Subject: Power sub station and me

just a guess but could it be that the act of sleeping with earplugs in is causing the headaches? perhaps some sort of positive or negative pressure on the eardrum?

measuring EM fields will require specialized test equipment and the expertise to make the tests and interpret the results. i would first approch your power company to see if thier feild engenering department would make the tests. the may even refer you other valid sources of information.

there has been some research on the effects of sound on the human body, however much of it it sill shrouded in myth and fokelore. it is beleived that sound or light pulese between 10 and 30 PPS (pulses per second)

measuring low level audio in no easy task either. especially at the low frequencies. most meters are A or C weighted. both roll off the extreme lows. a system that uses a calibrated referance mic, a computer system with SMAARTLIVE or equivelant software might give you some meangful data IF the sound is well above the ambiant background sound level. you may find someone set up with this kind of rig at a sound compant that does jobs at large venues or contractor who regularly installs sound for large and critical venues. if i had to hazard a guess, based on insuficient data, i would guess that you will fine that the fan noise from a desktop PC much loider then the noise from the substation,,, when measured in your living room.

some other possibilitys to consider: gas leak, carbon monoxide, mold.

im truly sorry for your pain. i would check the easy stuff first before exploring exotic possible causes. i hope all becomes well with you.

Well, for something like this, you can sit and concentrate on it all day so it anoys you, or you can ignore it and you'll forget about it. I have continuous loud tinitus in one ear but I just ignore it and don't even think of it unless someone mentions such things. Some people concentrate on their tinitus and it drives them mad (although they may have a different type from me).

Classic stress.

Classic bad posture at a keyboard/screen.

Could be stress again.

Not coincidental at all. It ties up exactly with you working from home in a new working environment. You need to have your (home) workplace assessed by someone trained in Display Screen Equipment assessments/regulations. Your employer is required to have a policy on this. Typically this will say something like anyone using a keyboard/screen for more than 2 hours a day should be trained in the regulations, spotting the symptoms of wrong posture (which you have perfectly described above), and solving them. You should also have a trained assessor watch you working normally at your keyboard/ screen once a year or so, to warn of any posture problems you can't see for yourself. This will include checking you have a suitable desk, chair, footrest (if necessary), keyboard, mouse, and monitor (laptops generally fail to meet display screen equipment regulations).

You should also go to an optician to get your eyes checked (specifically mention the symptoms above -- your optician will instantly recognise them) and if you use varifocal glasses, you may need a new pair for VDU use (your employer should pay for the checkup and glasses required for work).

Secondly, consider if the hum is stressing you. Sitting there concentrating on it and grinding your teeth won't make it go away; it will just stress you out. Try to ignore it. You could also contact the local electricity company to get it fixed (probably won't get far).

Start with the more obvious cause, as I've outlined above.

Ear plugs seem to do nasty things to my inner ear.

Some Google diversions: noise canceling headphones. also: noise blocking fence

Andrew - I have been an IT professional for 14 years now. I know how to set my desk up but thanks for the info :)

Anyway thanks for the posts guys but the TMJ one is almost certainly correct. I blame my new dentist and the ear plugs going in every night. Still shouldn't be allowed to make that damn noise at night. It's louder than a van running outside the window.

You have to believe me, the pain is so bad sometimes that if I thought it would work I would wear it ;)

Sorry to hear that, I was just pulling your leg

Regards

Daveb

| Andrew - I have been an IT professional for 14 years now. I know how to | set my desk up but thanks for the info :) | | Anyway thanks for the posts guys but the TMJ one is almost certainly | correct. I blame my new dentist and the ear plugs going in every night. | Still shouldn't be allowed to make that damn noise at night. It's | louder than a van running outside the window.

Could you take a portable audio recorder and start recording this sound, starting from inside you house? Periodically talk in a normal voice to describe where you are and how far in meters from the substation you are as you walk in the best path to go there. Then convert to a WAV file and put it online. An MP3 is OK, too, but a WAV file may be important.

Probably the hum is corona discharge, thus the very strong electric field around the conductor of HV lines (V~400 kV) ionizes air.Did you consider going to the psychiatrist?My aunt, mentally a very healthy person, and with a good health, generally, suffered from terrible headaches (migraines) all her life, and no doctor found anything.Now she takes antidepressant, and the headaches have stopped.

-- Tzortzakakis Dimitrios major in electrical engineering, freelance electrician FH von Iraklion-Kreta, freiberuflicher Elektriker dimtzort AT otenet DOT gr Ï "operator jay" Ýãñáøå óôï ìÞíõìá news:hxwge.2813$ snipped-for-privacy@news1.mts.net...

Not likely. Corona discharge produces more of a crackle or frying sound. If its a substation with a transformer, its the core generating an audible hum due to the magnetostricitve effect. The change in flux density within the core causes it to expand and contract slightly.

Hmm (no pun intended). This might be an excellent application for active noise cancellation. The source has a constant amplitude, frequency and harmonic content. Its a relatively low frequency, 50 Hz and a few harmonics and you really only need to cancel it at a fixed position.

In alt.engineering.electrical Paul Hovnanian P.E. wrote: | Mirth wrote: |> |> Andrew - I have been an IT professional for 14 years now. I know how to |> set my desk up but thanks for the info :) |> |> Anyway thanks for the posts guys but the TMJ one is almost certainly |> correct. I blame my new dentist and the ear plugs going in every night. |> Still shouldn't be allowed to make that damn noise at night. It's |> louder than a van running outside the window. | | Hmm (no pun intended). This might be an excellent application for active | noise cancellation. The source has a constant amplitude, frequency and | harmonic content. Its a relatively low frequency, 50 Hz and a few | harmonics and you really only need to cancel it at a fixed position.

Wouldn't that be 100 Hz if it's magentostriction?

| Probably the hum is corona discharge, thus the very strong electric field | around the conductor of HV lines (V~400 kV) ionizes air.Did you consider | going to the psychiatrist?My aunt, mentally a very healthy person, and with | a good health, generally, suffered from terrible headaches (migraines) all | her life, and no doctor found anything.Now she takes antidepressant, and the | headaches have stopped.

When I hear corona discharge on 765kV lines (right next to where one of my relatives lives), it doesn't sound much like a hum.

I would suspect magnetostriction in a transformer. But in this case that would have to be rather loud. I'm wondering if it is something else and is being caused by stray ground return currents on the branches going out.

True. But its still a (relatively) simple problem compared to other proposed active cancellation applications.

Actually it is full of harmonics due to the vibrating metal parts and even the harmonics in the current waveform itself. Play a pure 50 Hz tone through a hi-fi speaker system and it has a clean deep bass sound, not a ringing transformer hum. John

In addition beg, borrow or rent an audio db meter. There are standards and if you can get recorded and verified noise levels, you have some ammunition to use. A WAV file does not give a non-objective measure of sound level.

------------ Still active cancellation works- it has been used.- It cancels harmonics as well as the fundamental-- Don Kelly snipped-for-privacy@peeshaw.ca remove the urine to answer