18048Re: HUM_FORUM: I think I may I have the German Hum shielding experiment sorted out
- Jul 1, 2014A few months ago I posted a pic of a lab in our building lined with cu. Hum was no different in it than any other lab not lined on the floor. Wonder how thick our cu is? Maybe I'll do some investigation.
Sent from Steve's iPhone and I appologize for typo's and auto corrects
On Jul 1, 2014, at 1:10 PM, "Glen MacPherson glen.macpherson@... [humforum]" <firstname.lastname@example.org> wrote:“Hum and Otoacoustic Emissions May Arise Out of the Same Mechanisms”, FROSCH, F., Private Initiative Brummton, Bad Dürkheim, Germany. Journal of Scientific Exploration, Vol . 27, No. 4, 603-624.The paper makes a mathematically rigorous and well-researched argument that the Hum arises from the same mechanism that creates Otoacoustic Emissions. Deming (2004) rejected this is as an explanation for the Hum. I found the overall thrust of the article quite convincing, until I re-read the following paragraph:“The evidence that hum does not derive from any external electromagnetic source, which hum-sufferers sometimes assume next after discounting an external sound-source for their hum, was supplied in 2006, when IGZAB eV board member and researcher Franz G. Frosch reported that hum is perceived unchanged in two validated locales. The first of those locales is a custom shielded chamber in Bad Durkheim consisting of electrolyte-copper sheets of 1 x 1 x 2 x 0.001 m. The second locale is a magnetically shielded chamber, specifically the BMSR2 chamber of the Physikalisch Technische Bundesanstalt in Berlin, with a shielding factor of more than 10^6 for frequencies of 0.01 Hz and upward. Hearers determined no difference in the hum-perception when stationed either inside or outside of these locales, therefore an instantaneous external electromagnetic cause for hum does not exist.”Look at the thickness of copper used: 0.001 m, which is the same as 1 mm. I’ve checked a number of sources, for example from the textbook provided by engineering Professor Milos Popovich from the University of Colorado. According to his and other references, 1 mm of copper will not even provide a single skin depth of copper, let alone enough shielding to fully block 1 kHz signals. Frosch could be correct in the end, but until a radio engineer or experimental physicist weighs in and contradicts what I write here, at this point I argue that we set aside conclusions based on his paper because the copper VLF shielding box used was not sufficiently thick to block VLF signals. Iron (mild steel specifically), as I’ve mentioned before, because of its very large relative permeability, is an ideal material for creating a shielding box. It’s skin depth at 1 kHz is 0.16 mm. That means that a 1.2 mm thickness (a standard production size) would provide 7.5 skin depths, which I compute to be at least 99.999% shielding. That is the material that I will use when I conduct the Deming Box Experiment.CheersGlen
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