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Stephen Shaw wrote:
> Hi Dave, Jean, etherealists all...
> the first thing apparent
> about why auroral sounds haven't been explained satisfactorily is that
> this is
> not a robust phenomenon at all. The accounts of the actual sound
> structure are
> variable, some hear the sounds when sometimes others in the same group
> don't,
> some individuals who hear them sometimes don't hear them most other
> times, and
> (perhaps related) this seems to depend on the local structure of the
> environment, etc. Some outside observers doubt it is a real phenomenon
> at all,
> and all seem to agree that the effects are not loud.
Hi Steve & All, Nov 17, 2006
I finally got around to visiting two of the sites, the more
informative being
http://members.tripod.com/~auroralsounds/
Your condensation of general experience (above) is what I would have
expected, based on personal experience. Hearing is not a constant, so
assuming hearing is involved, anyone with less than excellent hearing in
the rustle range would not hear it. I used to have very good hearing but
at our latitude (45o) heard only faint rustles when displays were
exceptional and of course nothing when displays were not exceptional.
Over the course of several nights at about 55o the sounds were obvious
but even these obvious sounds would easily have been swamped by a light
breeze (causes ears to roar) or background noise of any kind and perhaps
even by recent exposure to loud sounds (ears adjust relatively slowly).
So probably the minimum conditions to experience these sounds
includes a conjunction of good hearing, calm air, dead silence, no
recent exposure to loud sound and high latitude or exceptional displays.
The quotation from Robert Service is a bit garbled, sulphus should
be sulphur and life should be like. He apparently was hard of hearing.
The idea of electromagnetic waves in the audible range sounds
promising, in that they apparently have been routinely detected by
instruments, but the frequency of 4 kHz to 8 kHz does not register
directly with a rustle. So one would have to postulate out of phase
waves that produce a beat in the audible range.
I have not done this for many decades so don't recall details, but
audible beats at frequency x can readily be produced in a
radio by injecting a second signal that differs from anRF generating
circuit by x.
Yours truly, Dave Webster, Kentville
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