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In Reply to: RE: Ear sensitivity posted by op48no1 on April 8, 2011 at 19:48:49:
... when using a similar effective sized horn pickup array as a hearing aid and all correctly funneled into the ear. Still, I'm going to doubt it.
POWER OF VOYAGER II'S X-BAND TRANSMISSION FROM SATURN
PG / k1 x (r2)2 = 1,384,500 / (12.5664) x (1.3 x 1012 meters)2
1,384,500 / (1.6 x 1013)2 = 1,384,500 / 2.1 x 1025
= ======== 6.6 x 10^-20 watts/meter2 ==========
POWER FLUX DENSITY (PFD) = P x G / 4 x pi x r2
PFD = watts per meter2
P = 21.3 watts (X-Band transmitter output)
========= G = 6.5 x 10^4 (antenna gain) =========
PG = ERP (effective radiated power)
r = radius or distance from earth
Power received = 4.29 x 10^-15 watts = 4.29 femtowatts (fW).
Threshold of hearing = 0 dBA = 1.00 x 10^-12 watts = 1 picowatt (pW). A very tiny amount of energy.
Add power gain from a massive horn array into the ear, the same as the assisted antenna gain (just for a fun comparison, as if this could be done). The power gain was 6.5 x 10^4.
Ear sensitivity with this system then goes down to 1 pW / antenna gain = 1.54 x 10^-17 watts = 0.015 femtowatts. Now the ear clearly wins, and we are in a way somewhat wrong (might have to remove the outer ear's own gain for this idea).
It would be some kind of amazing radio receiver that could do 1 pW sensitivity with the kind of small size and weight portability and low energy needs as a human head with ears can do. I think microphones can, but the electronics ruins its very large dynamic range.
We can see by this comparison that the ear is a remarkable instrument, just by itself without the brain processing.
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Follow Ups
- Maybe the ear can match Voyager's small signal - kurt s 04/8/1121:00:49 04/8/11 (3)
- Numeracy - op48no1 13:59:38 04/9/11 (1)
- Well, let me state the assumptions I made - kurt s 17:10:56 04/9/11 (0)
- Kirt - Neff 07:07:57 04/9/11 (0)
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