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Sound-cancelling earplugs

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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.

MaxwellBuchanan, Nov 01 2010

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]

[link]






       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. [+]   

       (Would produce the effect of sudden total deafness -- would that be a pleasant or unpleasant sensation, I wonder?)
mouseposture, Nov 01 2010
  

       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.   

       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.)
MaxwellBuchanan, Nov 01 2010
  

       This makes me wonder what completely deaf (auditory nerve loss or damage) people 'hear'. Not likely unpleasant, I would think.   

       <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]   

       Oh, big bun [MB]. Well up to your usual standard.
Boomershine, Nov 01 2010
  

       If the sound was internal, wouldn't the hair cells get activated prior to the microphone?
leinypoo13, Nov 01 2010
  

       Does it get rid of the voices in my head, too?
daseva, Nov 01 2010
  

       [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."   

       [leinypoo13] That's what I was talking about in the first paragraph of my first annotation.
mouseposture, Nov 01 2010
  

       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.   

       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?
leinypoo13, Nov 01 2010
  

       [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.   

       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.   

       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.
mouseposture, Nov 01 2010
  

       Where would it put all this cancelled sound?
Ian Tindale, Nov 02 2010
  

       [IT] Since the ear*drum* is no longer being used, and the sound is canceled, couldn't it go into one of those?
Boomershine, Nov 02 2010
  

       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.
infidel, Nov 05 2010
  

       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.
ldischler, Nov 05 2010
  

       //match a virtual frequency// Worse than that -- wouldn't you have to match a virtual phase, too?
mouseposture, Nov 05 2010
  

       It's not intended to treat tinnitus. It's meant to cancel breathing and swallowing noises, as well as residual external noises.
MaxwellBuchanan, Nov 06 2010
  

       I was going to say all of what [mouseposture] said. Saved me a lot of typing there.
bigsleep, Nov 06 2010
  

       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.   

       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.
metarinka, Nov 07 2010
  

       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.   

       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.
metarinka, Nov 07 2010
  
      
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