On Sep 2, 2:42 am, (Paul Schlyter) wrote:

In article .com,

Radium wrote:

The radio-frequency EM radiation emitted from the sun does translate
to sound when it is picked up by a radio receiver of the same carrier
frequency.

Here you make the silent assumption that the electric signal from the
radio receiver is fed to a loudspekarer. But that's just *one*
possible way of converting the EM radiation. You could use other ways
too. For instance displaying it on some video screen - those who do
so could claim that "The radio-frequency EM radiation emitted from the
sun does translate to light when it is picked up by a radio receiver
of the same carrier frequency" (with the silent assupmtion that the
output from the receiver is displayed on a video screen). It's the
translator who decides what the EM radiation translates to....
Btw did you ever try to *listen* to a TV transmission? I mean, to feed
the *video* signal (not the audio signal) to a loudspeaker instead
of a video screen? Yep, the sound changes with the contents of the
picture - but of course one hears only the lowermost part of the 5 MHz
of bandwidth a normal video signal has.

I've done this before. Plugged the video signal into the audio
receiver. There is some buzzing sound. As you said, that sound changes
as video signal changes.

Another interesting experience is to feed a digital signal directly to
a loudspeaker instead of decoding and converting it to an analog
signal first. That of course requires that the digital signal is
within the audible range of frequencies -- the signal from a
traditional telephone modem would be quite suitable here. The old 300
bps modems produced a signal with a quite clear structure (the signal
jumped between two frequencies 300 times per second), but the more
modern telephone modems which can handle bit rates up to 57600 bps,
they sound pretty much like white noise to the human ear.

Interesting indeed. However, are those old modems really "digital"?

That's why audio software is often used to speed up the infrasound
until it is at least 20 Hz so that humans can hear it.

:-) ....there's no need to speed it up just to convert the frequency
into the audible range.... the frequency can be bumped up even if
the original speed is maintained.

Is this done using audio software such as Adobe Audition?

Quotes from http://www.adobe.com/products/audition/overview2.html :

"Time and pitch processing: Change tempo without shifting pitch - or
shift pitch without changing tempo - and never introduce audio
artifacts."

using an AM receiver as opposed to an FM receiver. FM is immune to the
disruptions that normally affect AM.

Did you ever try to tune an FM receiver between radio stations on the
FM band? Also turn off any "muting" or "squelch" the receiver may have.
What do you hear? Silence? Or perhaps noise?

White noise. Hissing. Nothing special.