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7180Re: Researcher asks: Anybody try to screen off the Hum with Faraday cage?

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  • andrewyassin
    Oct 4, 2006
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      Hi Rossen!

      We tried to match the hum to complex computer generated signals.
      It was not possible to get a good match, but my best estimate was a
      Squared-sine signal with base frequency of about 60-61Hz.

      My wife almost gave up, but pinned it down to something like 50-70 Hz
      but as a pure sine tone.

      I never thought of how we hear it - surely that means I hear it as if
      it affected both ears. But it seems more like it just appears inside
      my head - though I also often experience it as a vibration of some sort.

      Outdoors, I sometimes "feel" it in my feet.
      Note - the intensity varies significantly between relatively close
      spots. that we "hear" it most clearly indoors may very well be due to
      the much lower ambient noise levels. Indoors at our cottage in the
      Swedish countryside it is, according to my measuerements, extremely
      quiet. Well, except for the hum...

      I have managed to interest one of the foremost authorities in the
      world on vibrations and infrasound, but time and poor weahther may
      preclude a more detailed study this fall.

      Anyway - this old professor knows about the Taos hum, as well as
      similar "incidents" in north Sweden over the past 3-4 decades.

      Some cases could be explained by vibrations in the ground (turbines
      main frequencies), some could not.

      I'm currently trying to find data on the turbines in all hydroelectric
      power plants in the region. Hopefully I may be able to match such data
      to some measurable entity.


      Another theory is the 3G network that has grown exponentially around
      here. However unlikely due to the low fields, it is the one main
      difference during the last few years around here. The 3G system
      operates at 2.1GHz, and might possibly somehow (note the vague
      language ...) augment RF-induced effects synergistically with the
      older GSM (900MHz) system.

      To rule that out I'd like to try to shield off the RF-fields.
      But I don't want to reinvent the wheel. Surely somebody has already
      tried that?

      It is however not easy to create a good Farady cage. You did mention a
      few disadvantages of the steel box approach - acoustic resonances
      etc-, though your post seemed to be geared towards reducing also
      static magnetic fields.

      But a reasonably good shield should easily be possible to create using
      reinforced cloth such as that found at www.electrosmog.de

      Any experiences of the usefulness of a decent RF-shield?

      Cheers,
      Jaxz

      --- In humforum@yahoogroups.com, "Rossen" <brumnauka@...> wrote:
      >
      > Hello Jaxz,
      > What is the main frequency of your hum? Does your wife hear the same
      > frequency? Where do you and your wife hear the hum - in left, right
      > or in two ears?
      >
      > Rossen
      > Sofia, Bulgaria
      >
      > --- In humforum@yahoogroups.com, "andrewyassin" <jaxzjaxz@> wrote:
      > >
      > > Hi all,
      > > I hear the hum and so does my wife. This is in south Lapland, North
      > > Sweden.
      > >
      > > As a research physicist I have access to great instruments to
      > attempt
      > > to solve this puzzle.
      > >
      > > I have read a lot about the hum, and actually done some very precise
      > > acoustic measurements. However, the results were that there was NO
      > > audible signal present at all, even though I could hear it loud and
      > > clear while measuring.
      > >
      > > I could measure down to 6Hz with very high sensitivity (20dB L-Eq;
      > > that is linear response over the entire spectrum - no filters)
      > using a
      > > Bruel&Kjaer 2260 investigator.
      > >
      > > For infra-sound to be perceptible, very high signal levels are
      > usually
      > > required; that is above ca 90dB L-Eq at 16Hz and increasing with
      > > decreasing sound frequency.
      > >
      > > This is a truly amasing piece of instrumentation - in Nort sweden it
      > > could pick up a concorde starting in Paris. However, no luck with
      > the hum.
      > >
      > > Next week I'll do some vibrational studies as well using either a
      > > Geophone or an accelerometer. Such data might correlate to infra-
      > sound
      > > loggings made by the IRF at www.irf.se (institute of space physics,
      > > Umea university). Possibly my hum might come from hydroelectric
      > power
      > > plants. If so I'll surely be able to measure it.
      > >
      > > However, if the hum is of electromagnetic origin - it should be
      > > possible to screen off the perceived sound by creating a Faraday
      > cage.
      > >
      > > Did anybody yet rule out that possibility?
      > >
      > >
      > > Please post if you tried to screen it off using a proper cage!
      > >
      > > Best regards,
      > > Jaxz
      > >
      >
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