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From: email@example.com (milne_v)
Subject: Re: Any ideas on measuring radiation in the home ?
Date: 10 Oct 2002 17:14:52 -0700
References: <%_wk9.52964$1C2.firstname.lastname@example.org> <%email@example.com>
NNTP-Posting-Date: 11 Oct 2002 00:14:52 GMT
"News2020" wrote in message news:<%firstname.lastname@example.org>...
> There are even more sources of noise in a small urban neighborhood.
> Last night I found three more sources of 'weird' sounds and some other
> sources of loud sounds at night.
> One was a slow repeating bubbling sequence at midnight; one might mistake it
> to be a washing machine cycling slowly; it was quite loud enough to bother
> sleep. I went outside to check. The neighbor at the far end had his garage
> left open. The noise was coming from inside, getting reflected from the
> opposite building and reaching my house almost without loss of strength.
> Initially I thought it must be the washing machine inside. But, on second
> inspection, I found that it was not. It was coming from the water-heater
> area nearby. Possibly a hidden speaker set/transducer there ?
> Another was the new lighting outside the garage doors. Most of the old flat
> small bulbs have been replaced with compact coiled (antenna like)
> flourescent tubes. One of them was giving out a directional high-pitched
> audio tone pointed down the road.
> Even a community street light (yellow) (or its lamp post ?) was emitting a
> strong tone.
> Area utility transformers seemed to be emitting a buzz that could be heard
> 10 - 20 ft away - that was not too loud.
> Passing cars and trucks are significant sources of noise at night ! They are
> very loud. I found that garbage trucks are an order of magnitude louder than
> even that. Those trucks have something wrong with their construction.
> One interesting difference I noticed between last night and the night before
> was the total lack of background noise. The night before I had heard a very
> very loud background roar that I assumed was due to 'freeway traffic' - 1/2
> mile away. Last night that noise was completely missing ! I think this is a
> new source of noise that is yet to be identified. It is probably something
> originating from the airport area (farther away) and not at all traffic
> noise from the freeway ! It is hard to imagine heavy traffic at night on a
> freeway that would be needed to create such loud noise.
> Noise reduction/elimination must be made part of every design. Automobiles,
> homes, neighborhoods, even aircraft. < Passing aircraft completely blanket
> the whole area with noise of all kinds of frequencies ! >
> I believe this is achievable with today's technologies.
What is HSS?
HyperSonic Sound Technology is simply the most revolutionary sound
reproduction system of this century. Not since the development of the
"cone" loudspeaker more than 75 years ago has any technology provided
such significant departure from conventional loudspeakers and such a
remarkable new approach to the reproduction of sound.
The directivity (narrowness) of any wave producing source depends on
the size of the source, compared to the wavelengths it generates.
Audible sound has wavelengths ranging from a few inches to several
feet, and because these wavelengths are comparable to the size of most
loudspeakers, sound generally propagates omnidirectionally. Only by
creating a sound source much larger than the wavelengths it's
producing can a narrow beam be created.
Clearly, having loudspeakers twenty metres wide is not very useful.
to make a narrow beam of sound from a small acoustic source, we
instead generate only ultrasound.
The ultrasound, whose wavelengths are only a few millimetres long, are
much smaller than the source, and consequently travel in an extremely
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