7147Researcher asks: Anybody try to screen off the Hum with Faraday cage?
- Oct 2, 2006Hi all,
I hear the hum and so does my wife. This is in south Lapland, North
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!
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