SY, I think the whole angstrom claim stems from the fact that under the right conditions, it's possible to hear the thermal noise of the air itself as the air molecules randomly bang into the eardrum.
Assuming that's the case, the question then becomes, by what amount would those air molecules banging into the eardrum displace it?
se
Assuming that's the case, the question then becomes, by what amount would those air molecules banging into the eardrum displace it?
se
Hi All,
Its not simply just a question of displacment, that is just a number, its energy,
or power, or SPL, displacement drastically reduces with frequency, for the
critical 3kHz to 4kHz band the ears shape itself will amplify the signal to
more than implied by the simple mathematics that apply lower down.
The numbers (I have not worked them out) probably represent an equivalent.
I guess your talking about the equivalent displacement @4kHz for ~ -10dB.
It may be a higher frequency with lower displacement but a higher dB level.
/Sreten.
Its not simply just a question of displacment, that is just a number, its energy,
or power, or SPL, displacement drastically reduces with frequency, for the
critical 3kHz to 4kHz band the ears shape itself will amplify the signal to
more than implied by the simple mathematics that apply lower down.
The numbers (I have not worked them out) probably represent an equivalent.
I guess your talking about the equivalent displacement @4kHz for ~ -10dB.
It may be a higher frequency with lower displacement but a higher dB level.
/Sreten.
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It is not the dB that you divide for that, but the amplitude. If you calculate in dB you need to subtract the attenuation. 16000m give some 168db attenuation (just for inverse square law, no friction losses), so the final signal would be at -96dB. Air friction losses would drive that even lower.
Yes. A reliable secondary source for that kind of data is Fundamentals of Acoustics by Lawrence Kinsler and Austin Frey, published by John Wiley & Sons. They state that the human ear can respond to sound pressures on the order of .0001 microbars, which corresponds to a displacement of the eardrum of .01 nm, which is roughly 1/10 the diameter of a hydrogen gas molecule, not 1/100.
The changes in pressure due to thermal agitation of gas molecules falls below this threshold, so despite extraordinary claims, this type of noise is inaudible.
Interestingly enough, although the ability to hear higher frequencies fades with age, the ability to detect these miniscule changes in pressure and corresponding displacement of the eardrum in the range of 1kHz to 5kHz stays with us.
John
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When you think about it this thread has gone pear shaped. So all this calculations and headscratching because some nutty said you could hear a piece of chalk drop ten miles away from you. Ask a normal person and he will need five seconds to get that right. No way.
What difference does it make anyway? This has nothing to do with audio electronics concerning the human ear. Is it possible for audio engineers to build an electronic device that will have the same capabilities that the human ear has? No it isn't.
When you think about it this thread has gone pear shaped. So all this
calculations and headscratching because some nutty said you could
hear a piece of chalk drop ten miles away from you. Ask a normal
person and he will need five seconds to get that right. No way.
What difference does it make anyway? This has nothing to do with
audio electronics concerning the human ear. Is it possible for audio
engineers to build an electronic device that will have the same
capabilities that the human ear has? No it isn't.
Hi, I quite agree, its just playing with numbers not reality, rgds, /sreten.
Though FWIW electronic signal processing and decent mikes can do lots
of things the human ear is totally incapable of, such as dig out a slow
signal from e.g. 60dB of noise, and mikes are intrinsically more accurate
and can show loads of things that human perception is incapable of.
That makes sense - there is no survival advantage in evolving a hearing mechanism that's more sensitive than the environmental noise limits.
A similar situation exists with microphones. Smaller diaphragms are preferable to larger, especially for measurement work, and good preamps are now so quiet that they don't contribute significantly to the noise figure. The limiting factor is brownian motion noise, which gets worse as the diaphragm area reduces.
Assumption: people who write popular articles about science have very good imagination.
But... I recently heard a lecture of a scientist that studied subconscious reactions on different kinds of sounds. What they've found, was something different from what they intended to study.
They found that people react before they heard certain sounds!
They started working with pictures as well that cause different emotions, and found that emotion reactions happen as well before!
How to explain that?
Nobody has any strict theory, but many institutes and laboratories work on it at least last 12 years, and have a lot of unexplainable data.
What do I mean?
I mean that all explanations of mind from machine-like theories don't corellate with empirically obtained results.
But... I recently heard a lecture of a scientist that studied subconscious reactions on different kinds of sounds. What they've found, was something different from what they intended to study.
They found that people react before they heard certain sounds!
They started working with pictures as well that cause different emotions, and found that emotion reactions happen as well before!
How to explain that?
Nobody has any strict theory, but many institutes and laboratories work on it at least last 12 years, and have a lot of unexplainable data.
What do I mean?
I mean that all explanations of mind from machine-like theories don't corellate with empirically obtained results.
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Yes, it is crazy!
I have an audio record of the lecture, but have no rights to distribute it. The name of the lector was Dean Radin, PhD. The lecture was called Common Sense and Evolution of Reality.
Dean Radin - Bio
Its not an explanation but this is entirely in keeping with Benjamin Libet's work decades ago. He found that people made a decision (actually there was measurable 'readiness potential') to move their finger a few hundred mS before they became aware of making that decision.
Conclusion - our conscious awareness lags behind 'real time' by a not insignificant amount.
My patience has been rewarded, many interesting comments has been posted since I made that remark.
Yes, but they're still unable to build a robot that walks properly.
If you're interested in crazy ideas I suggest you to read the works of Carl Jung.
Yes, conscious awareness always comes second.
Yes, but they're still unable to build a robot that walks properly.
YouTube - Boston Dynamics PETMAN Prototype
And check out their Big Dog. Really wonderful work.
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