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    Detecting the existence of a sound that has been lost in thermal noise

    GTrax, Are the "beats" caused by the sound pressure waves from one source messing with the vibrations of the other source in a non-linear way? .. or do the waves arrive and mix and interfere with each other producing "beats", as opposed to simply adding in pure fashion? Here's a fairly obvious...
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    Detecting the existence of a sound that has been lost in thermal noise

    Gtrax That's a good, controlled, experiment you did. In virtually all the related professional research I've read on the topic, control is woefully inadequate imo. Are you fairly confident that your 8k tinnitus is a fairly pure tone? You would of course still get a beat frequency if it is...
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    Detecting the existence of a sound that has been lost in thermal noise

    Sorry, I think I messed up by mentioning my friend's tinnitus as it has taken us off topic, and detracted from the physics question I wanted to consider. The question is really "Is there any way of detecting a sound that cannot be heard". An example of an answer might be "Yes, if you can see...
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    Detecting the existence of a sound that has been lost in thermal noise

    Suppose there is a quit sound inside the centre of a spherical box. the sound is so quiet that it cannot carry beyond the surface of the box. - at that distance from the source it is much quieter than the natural thermal noise of the box. It cannot be heard with even a perfect microphone...
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    Detecting the existence of a sound that has been lost in thermal noise

    Hi Evo, I have been heavily involved with tinnitus charities and personally with some of the researchers in the field. The people involved largely overlap and understandably interact and know each other. Generally the medical-science approach is to describe it as neurological, and that flows...
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    Detecting the existence of a sound that has been lost in thermal noise

    Berkeman, I am thinking along the lines of a noisy stray capilliary, that has grown in the wrong place. Something much smaller than (what I'd think of as) an anneurysm. Maybe it could even be the normal surface noise of a tiny blood vessel ,ordinarily inaudable, but in this case so close to...
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    Detecting the existence of a sound that has been lost in thermal noise

    ultra sensitive microphone or technique for listening to inner ear A friend has very loud tinnitus. He says it is constantly louder than anything else he can hear. Nothing can be heard by an independant observer such as myself, but it is possible that a sound with a small power level is so...
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    Software to make line graph, Like Excel?

    Gnuplot does the trick. Matlab - £3,000. The opposite of free! Many thanks Tony
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    Software to make line graph, Like Excel?

    Is there any software that will convert a series of numbers into a simple line graph, the same as Excel, but allowing me to use a lot more numbers? I'm writing a program in c to convert a sinewave, or any wave, into a triangular wave. I've sort of done it, but there is noise in my...
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    Cant spot flaw in nested logic in puzzle

    Yes you got the idea :-) And I understand what you're saying, but although it obviously is invalid, I still don't really see why "perception of perception of perception" becomes invalid. "Perception is valid." (Angus thinks...) "Perception of perception" is valid (Angus thinks that Ben...
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    Cant spot flaw in nested logic in puzzle

    Each dragon can see all three other dragons. They can all see each other. They all have green eyes. None of the dragons know this since they don't know their own eye colour. Each dragon can therefore see 3 pairs of green eyes. There are no possible colours besides green and brown. Consider...
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    Cant spot flaw in nested logic in puzzle

    This is not a puzzle question exactly. It's a question about logic that the puzzle illustrates. There are four dragons. It is known that dragons can have brown eyes but our four all have green eyes. They can see each others eyes, but don't know their own eye colour. They will turn into...
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    Evolution -How many times did life begin on earth

    Hi Chemisttree, wow some strongly expressed views :-) Good points though. I imagine that suddenly the conditions were just right, and the same chemical reaction giving rise to life happened simultaneously in a lot of places, and all these life-molecules were able to interact. But I'd...
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    Evolution -How many times did life begin on earth

    It's a good theory though. Perhaps, once the first 'life' had evolve, it spread around the globe very quickly and adopted its position of dominance. The reason I was wondering is: If we could show that life started more than once on Earth, it'd suggest that extra-terrestrial life is more...
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    Evolution -How many times did life begin on earth

    I get the impression that all life on earth, including extinct life, goes back to the same single common source. Is this the general view? Or could life have started out independantly at different times and/or places. If so is there any evidence? Tony
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    Medical Finger tapping test L-R inequality

    Yes. I wonder what the typical discrepency in dexterity is between the fingers of the dominant and the secondary hand.
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    Medical Finger tapping test L-R inequality

    Alternately tapping my first and second finger.... I can do this 20% faster with my left hand than my right hand. Is it possible to speed this up, or is it a fixed property of my adult nerves?
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    NASA NASA Chief on Global Warming

    Global warming is caused by the desire of politicians to get the public interested in 'something else'. :cool:
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    Global warming case frustrating

    Thanks again; I understand the analogy, and can now why this should apply to CO2, and to transparant paint too, which I'd never thought about. I will work on the Modtran material to understand it properly.
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    Medical Human Ear perceptions of sound

    There are 2 theories, phase and loudness. It may be just that the loudness in the left ear is greater than the ear is greater than the right, indicating that the sound is to the left. The tone of a familiar sound will suggest that it is in front or behind The brain also uses reason to figure...
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    Medical Time Perception Acceleration

    I'm learning some fast pieces on guitar. I've noticed that sometimes as I master the speed of a piece, time appears to slow down, so that I have time to get all the notes in, (or more likely my brain speeds up). I wish I could make it happen at will. I imagine it's the same phenomenon as when...
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    Global warming case frustrating

    Thanks Andre, Interesting reply, and thanks for introduction to Modtran, but my question really is: Why is it 0.7-1 deg C per doubling of CO2. Why isn't it a linear relationship - What is the basis in physics for the calculation that gives that result? Thanks Tony
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    Global warming case frustrating

    Effect of doubling CO2 - why logarithmic and not linear? How does a 30% to 50% increase in CO2 predict a 2-5 deg C temperature rise? Is there a formula? Why is the effect on low altitude atmosphere temperature effect of increasing CO2 logarithmic? I would have thought it would be linear...
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    Atmosphere temperature gradients at altitudes impossible?

    I think I understand that. Charles's law! V/T=constant So I should be able to calculate that and prove it to myself. :smile: Thanks to all. Tony
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    Atmosphere temperature gradients at altitudes impossible?

    But if the air molecules at an altitude of 20km had less kinetic energy than the bordering, encapsulating air molecules above and below, wouldn't they eventually reach at least the energy of the cooler of the two borders? I can't understand how any object can be permanantly cooler, or...
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    Atmosphere temperature gradients at altitudes impossible?

    atmosphere temperature gradients at altitudes impossible?? Here's a link to a graph: http://vortex.plymouth.edu/atmosphere/layers.html" [Broken] I don't understand how this is possible. The atmosphere is Warm at the surface, (due mainly to infrared heat from earths' surface -ok) Cold...
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    Does a hydrogen baloon ascend faster than a helium baloon

    Does a hydrogen baloon ascend faster than a helium baloon? Ignoring the weight of the baloon fabric, and ignoring friction, but not ignoring the mass of the air, would a hydrogen baloon ascend twice as fast? Would the same logic apply to lead and aluminium weights falling through water...
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    Earth's surface temp without atmosphere vs moon's

    So in the middle of winter, when the outside temperature is 0 C, if I have a cup of coffee at 100C and another at 50 C, the first will cool by 50 degrees a lot faster than the second :-)
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    Earth's surface temp without atmosphere vs moon's

    Without an atmosphere, the earth's average surface temperature would be -18 C. The moon's surface temperature averages -23 C. Is this 5 degree C difference due to heat from the earth's core? (I'm not a student; I'm curious about the climate debate, and trying to figure some things...
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    How to calculate the temperature of an insulated heat emitting body?

    Hi Fred I was wondering about the insulating effect of the atmosphere on the earth, hence the question. The graphs of pipe insulation are interesting but puzzling. It looks like the temperature difference accross the insulation is proportional to the log of heat loss. I dont understand why...
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