From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: Coming soon to a theatre near you - endless mischief potential
Date: Sat, 12 Oct 2002 17:52:04 GMT
NNTP-Posting-Date: Sat, 12 Oct 2002 10:52:04 PDT
John Larkin wrote:
> On Sat, 12 Oct 2002 17:40:18 +0100, John Devereux
> >John Larkin
> >>On 12 Oct 2002 06:13:17 -0700, firstname.lastname@example.org (milne_v) wrote:
> >>>We've heard hypersonic sound. It could change everything.
> >>>by Suzanne Kantra Kirschner
> >>> It's the most promising audio advance in years, and it's coming this
> >>>fall: Hypersonic speakers, from American Technology (headed by the
> >>Total, silly nonsense. Air is not a nonlinear medium, at least at
> >>non-lethal levels.
> >You're probably right... but what about the inside of your
> I believe that eardrums are slightly nonlinear (I bet John W knows
> something about this) so might serve as a mixer/detector for very high
> levels of two-tone ultrasonics. But even 30 KHz is hard to make into a
> tightly directional beam (as in the lifeguard example) and the levels
> would certainly have to be high, certainly dangerous, to produce even
> a barely audible response. Besides, the invention claims that the
> sonics are created in air, and that the sonics are somehow confined by
> the ultrasonics, and doesn't lose volume for 150 yards. Stupidity.
> Popular Science prints this sort of impossible crap all the time.
There are some curious effects having to do with the ear. These are
mentioned in the literature. A particularly striking one is that beats
can be heard when two tones are heard one in one ear and the other in
the other ear. I don't know if this has been completely explained. The
ear is very sensitive to beats to the point of exagerating them. In
tuning a piano, I can just barely hear the fork while the note I am
tuning is quite loud. The beat between the fork and the string is very
pronounced. Beat frequencies below 0.1 Hz are quite easy to hear. Of
course, beats are a linear phenomenon. The ear is simply a frequency
sensitive AC pressure detector. (If you have a bad cold, it may become
sensitive to DC which is quite uncomfortable.)
Popular Science has been OTL going back to the 1950s. One of the most
idiotic things I saw them publish was the idea of landing jet aircraft
on a treadmill to reduce runway length. I think cluelessness is a
requirement for any editorial or reporting job on the magazine.
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons email@example.com