h a l f b a k e r yWarm and Fussy
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I sometimes use earplugs on planes, or in other noisy situations
where I'm trying to sleep.
They are quite effective at blocking noise from outside, but they
make noise from inside louder: breathing or swallowing become
loud and annoying, offsetting the value of the earplugs.
So, MaxCo.
is proud to introduce its NoiseBeGone active earplugs.
Each earplug has a replaceable, disposable foam outer sleeve. Inside
is a slim cylinder containing a button cell, teeny tiny speaker, teeny
tiny microphone and some cunning circuitry. Most cunning of all, the
microphone points inward, rather than outward.
The teeny tiny microphone picks up not only any residual external
noises which have got past the foam, but also the noises of breathing
and swallowing which originate inside. Noise cancellation is then
actively applied to the teeny tiny speaker, to offset all noises and
create perfect peace.
Sony's version (outward pointing mic)
http://www.sonystyl...8198552921666073698
Active noise cancellation in earbuds [csea, Nov 01 2010]
No words, no thoughts
http://www.radiolab.org/2010/aug/09/
Nothing much to do with this MaxCo's device [Boomershine, Nov 01 2010]
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Annotation:
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At first, I thought this wouldn't work because you'd have to
cancel sound (pulse, temporomandibular joint crepitus,
maybe breathing) which reached the cochlea bypassing the
ossicles (and bypassing your microphone). Then I realized
that such sounds would be transmitted backwards through
the ossicles, with the typmanic membrane functioning like
a speaker, to vibrate air in the external auditory meatus.
The cute thing about this is, you don't need any inverse
models for ossicles or meatus, as long as the transfer
functions are invertible. [+] |
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(Would produce the effect of sudden total deafness --
would that be a pleasant or unpleasant sensation, I
wonder?) |
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I worried about the same thing, and came to the same
conclusion. I think it would be pleasant, at least based on
the few times when I've been somewhere totally quiet. |
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However, it should also be possible to deliberately add a
small amount of red or white noise (besides cancelling the
unwanted noises), which would be soothing if you were
trying to sleep. (I think another idea here proposed earplugs
that just make white noise, though.) |
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This makes me wonder what completely deaf
(auditory nerve loss or damage) people 'hear'. Not
likely unpleasant, I would think. |
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<sidenote> I recently read an article about a 27
year old man who was deaf his whole life, but *did
not know* he was deaf. He did not even realize
things had names or why other deaf people were
signing to each other. He just mimicked them.
Very weird thing to consider. When he finally
made the breakthrough, he broke out in tears.
Some years later, his mentor wanted to interview
him about his experience of life before he had
'words'. He claimed to have no memory of that part
of his life. The conclusion: no words=> no
memories, no 'thoughts.' ,</sn>. [link] |
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Oh, big bun [MB]. Well up to your usual standard. |
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If the sound was internal, wouldn't the hair cells get activated prior to the microphone? |
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Does it get rid of the voices in my head, too? |
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[8th_of_7] I have an invention I want to sell to BorgCo. A
virus which infects the DSP firmware of the MaxCo noise-
cancelling earplugs. //perfect peace// ... and a voice inside
your head saying "Join us. Resistance is futile." |
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[leinypoo13] That's what I was talking about in the first
paragraph of my first annotation. |
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I probably don't get what you are saying, because I don't understand how the ear or noise canceling works, but when sound comes through the eustachian tube, won't it activate the ossicles and cochlea, prior to activating the tympanic membrane. |
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Then the hair cells would ostensibly be firing off potentials (hearing), while the sound was traveling out of the ear to the microphone in order to be cancelled and be too late? |
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[leinypoo13] Ah, I see what you mean. True, but I don't
think it'll be a problem. See if the following holds water
for you, and let me know if I've overlooked anything. |
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Suppose a click travels from the temporomandibular joint
to the cochlea, and thence, via the malleus, incus, &
stapes to the eardrum. Distance from cochlea to eardrum,
in round numbers 0.01m. Speed of sound through soft
tissue: use the figure for water, in round numbers:
1500m/s. The lag, therefore, on the order of 7
microseconds. Upper limit of human hearing, say 20kHz,
reciprocal of which is 50 microseconds. So the lag, from
cochlea to eardrum, is about a tenth of a cycle, even for
the highest frequencies. The hair cell won't have time to
fire even one spike before the noise cancellation kicks in. |
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Or to put it differently, it's not so much a delay as a phase
shift. Which is where the stuff about inverse transfer
functions comes in. |
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[IT] Since the ear*drum* is no longer being used, and
the sound is canceled, couldn't it go into one of
those? |
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Hmmm <silently hums to self>... It's still not going to have any effect on tinnitus, is it? That's often more neurological than physical in origin. |
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Sort of like bungston's Tinnitus cure, which is a little more difficult to achieve in practice, as you may have to match a virtual frequency. |
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//match a virtual frequency// Worse than that -- wouldn't
you have to match a virtual phase, too? |
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It's not intended to treat tinnitus. It's meant to cancel
breathing and swallowing noises, as well as residual external
noises. |
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you know the microphone could be located anywhere on the head, probably further down the neck or jaw area would be ideal, since internal sound is carried via conduction through a solid you would want a microphone closer to sources so that your processor would have more time to react.
Also the circuitry would have to be quite advanced or calibratable to try to match the inverse frequency of sounds eminating from different parts of the body, that's why noise cancellation is never a perfect 1 to one for anything other than simple wave forms and non complex environments. |
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my college roommates thesis was on using computer speakers to cancel the hum of fans and hard drives but the level of active cancellation was never that high. |
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you know the microphone could be located anywhere on the head, probably further down the neck or jaw area would be ideal, since internal sound is carried via conduction through a solid you would want a microphone closer to sources so that your processor would have more time to react.
Also the circuitry would have to be quite advanced or calibratable to try to match the inverse frequency of sounds eminating from different parts of the body, that's why noise cancellation is never a perfect 1 to one for anything other than simple wave forms and non complex environments. |
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my college roommates thesis was on using computer speakers to cancel the hum of fans and hard drives but the level of active cancellation was never that high. |
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