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In Reply to: Maybe the ear can match Voyager's small signal posted by kurt s on April 8, 2011 at 21:00:49:
Kurt, thanks for doing those cacluations. The point of my posting wasn't to dismiss the remarkable capabilities of the ear/brain, but to give some perspective on the lightbulb example.
An incandescent bulb has an efficiency of about 2%. So we're talking about detecting an unmodulated 1.2W source from an isotropic radiator at a distance of 5000km. Not bad, but consider that ham radio operators routinely transmit and receive actual information over even longer distances using simple, portable, battery-powered equipment of 1W output or less (QRP). And the comparison isn't really fair to the ham operators, because they have to contend with atmospheric noise and absorption, whereas the bulb example assumes transmission through empty space.
Granted, the Voyager example involves high-gain antennas, but we were comparing the naked ear to electronic instrumentation. I would say that it's fair game to allow any sort of gadgetry on the instrumentation side. On the other hand, I would argue that your hypothetical acoustical horn array is just another kind of instrument that extends the capabilities of the senses, just as an oscilloscope or distortion analyzer allows us to perceive things we cannot with unaided eyes and ears.
What's really interesting, IMHO, is the question of numeracy, the ability to reason with numbers. Now, the distance from Earth to Saturn is about 240,000 times greater than the distance from NY to LA. That's about how much farther the moon is from Earth than the convenience store is from your house. I think this illustrates that, in the grand scheme of things, LA really isn't that far from NY.
So, to the extent that we're comparing the sensitivity of the ear to that of instrumentation, I would say instrumentation stacks up pretty well, wouldn't you agree?
-Henry
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Follow Ups
- Numeracy - op48no1 13:59:38 04/09/11 (1)
- Well, let me state the assumptions I made - kurt s 17:10:56 04/09/11 (0)
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