Turn Your House Into Noise Cancellation Headphones

[John Larkin]

On Sat, 17 Sep 2011 11:38:07 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Friday, September 16, 2011 3:16:54 PM UTC-7, John Larkin wrote:
On Fri, 16 Sep 2011 13:37:49 -0700 (PDT), whit3rd <whi...@gmail.com
wrote:

For more on this subject, refer to Arthur Clarke's _Tales from the White Hart_,
especially the chapter entitled "Silence Please".


Is that the story where the noise canceler exploded? I thought it was
hokey at the time...

But consider: the power output of the device has to cancel sound,
thus reducing the energy in the room. So, the device would, necessarily,
have a negative power factor on its (hypothetical) electrical-output-power
meter. Most of the practical amplifier devices we use have bias restrictions
that make the power-delivered-to-the-battery always nonpositive,
but some hypothetical device might not share that feature.
It always obeys the conservation of energy, though.

COE is part of the problem. If a transducer were somehow intelligent
enough to cancel the sound pressure at some usefully distant volume in
a room (unlikely, but take it as a hypothetical) it will be net
outputting sound. The original noise and the "cancelling" sound all
bounce all over the place, some getting absorbed, some coming back
from every which direction, with bizarre frequency profiles and phase
shifts from room features and resonances, adding to the general chaos.

In reality, speakers aren't very efficient, and certainly don't make
very efficient microphones. And filter caps can't store enough energy
to destroy a house.

Earplugs!

John

 

[Michael A. Terrell]

John Larkin wrote:

In reality, speakers aren't very efficient, and certainly don't make
very efficient microphones. And filter caps can't store enough energy
to destroy a house.

That depends on how many filter caps you drop on the house, and how
far they're dropped. ;-)


--
You can't have a sense of humor, if you have no sense.

 

[Bret Cahill]

The problem with noise canceling ear protection is...

   ... is that you've never owned a pair that work, and perhaps don't
   understand the physic involved. Mine work beautifully.

With other people in the room, however, it's anti social in the same way
as lap swimming.  They are right next to you yet you cannot talk.

And speaking of swimming, your ears don't seem to have to be very far
under water to almost eliminate noise.  A couple of inches is enough.  
If the active noise reduction is too difficult maybe water jacketing the
room would be the most cost effective solution.  You could still have
sunlight coming in through the windows.

Water transmits sound VERY WELL. Whales and dolphins know this, and you
can too!

That's true for water-only sound transmission. What is probably
stopping sound originating in air when you are swimming under water is
the air - water interface.

The hard part of sound proofing a room using that approach will be to
get a vertical air - water interface.

A viscous 2-phase gas - liquid foam sandwiched between two panels
should work even if it was pretty thin but that may not be any better
than the gas - solid foams used in conventional sound proofing.

Obviously you can't see clearly through a foam but if you could find
something a little more viscous than aloe vera you could have clear
glass sound proofing.


Bret Cahill

 

[Bret Cahill]

The problem with noise canceling ear protection is...

    ... is that you've never owned a pair that work, and perhaps don't
    understand the physic involved. Mine work beautifully.

Talking out of your ass is what you do best, worm.

   Marvin, you appear to be just plain ignorant about so many things.
   And so stubborn about educating yourself about the relevant science.

It's much worse than that. A "libertarian" cannot even apply the
most simple most basic logic to his [supposedly] most cherished
subject: freedom, free markets and free speech. For example, just
ask any "libertarian" The Question, "Does free speech precede each and
every free trade?" and he'll start dodging as though his life depended
upon it.

Expecting someone that dizzy and confused to apply even middle school
level math is a farce.

And it goes downhill from there.


Bret Cahill

 

[whit3rd]

On Friday, September 16, 2011 3:16:54 PM UTC-7, John Larkin wrote:

On Fri, 16 Sep 2011 13:37:49 -0700 (PDT), whit3rd <whi...@gmail.com
wrote:

For more on this subject, refer to Arthur Clarke's _Tales from the White Hart_,
especially the chapter entitled "Silence Please".

Is that the story where the noise canceler exploded? I thought it was
hokey at the time...

But consider: the power output of the device has to cancel sound,
thus reducing the energy in the room. So, the device would, necessarily,
have a negative power factor on its (hypothetical) electrical-output-power
meter. Most of the practical amplifier devices we use have bias restrictions
that make the power-delivered-to-the-battery always nonpositive,
but some hypothetical device might not share that feature.
It always obeys the conservation of energy, though.

 

[Rich Grise]

John Larkin wrote:

On Fri, 16 Sep 2011 13:37:49 -0700 (PDT), whit3rd <whit3rd@gmail.com

For more on this subject, refer to Arthur Clarke's _Tales from the White
Hart_,
especially the chapter entitled "Silence Please".

http://www.ebay.com:80/itm/TALES-WHITE-HART-Clarke-SIGNED-LTD-DELUXE-OOP-/390193852530

Is that the story where the noise canceler exploded? I thought it was
hokey at the time, the idea that the filter caps in the power supply
would store the absorbed sound energy and blow up the building.

The original poster was Bret Cahill.

Cheers!
Rich

 

[Rich Grise]

Michael A. Terrell wrote:

John Larkin wrote:

In reality, speakers aren't very efficient, and certainly don't make
very efficient microphones. And filter caps can't store enough energy
to destroy a house.

That depends on how many filter caps you drop on the house, and how
far they're dropped. ;-)

That would work with a box of rocks as well - the energy isn't in the

capacitors or rocks, it's in their momentum, which came from whatever
it took to loft them to bombing altitude.

Hope This Helps!
Rich

 

On Sat, 17 Sep 2011 07:51:55 -0700 (PDT), Bret Cahill
<Bret_E_Cahill@yahoo.com> wrote:

The problem with noise canceling ear protection is...

   ... is that you've never owned a pair that work, and
   perhaps don't understand the physic involved. Mine
   work beautifully.

With other people in the room, however, it's anti social in the same
way as lap swimming. They are right next to you yet you cannot talk.

And speaking of swimming, your ears don't seem to have to be very far
under water to almost eliminate noise. A couple of inches is
enough. If the active noise reduction is too difficult maybe water
jacketing the room would be the most cost effective solution. You
could still have sunlight coming in through the windows.


Bret Cahill

No problemo - full duplex spread spectrum radio links between headsets

with built in bone conduction microphones. Then the trick is making
them small enough to be unobtrusive.

Water jackets? Bury them down 1,000 feet. Unless the whole idea was
to watch fighter jets take off - in which case the triple pane windows
might move enough to blur the image.

Water jackets - you'd need some means of killing algae and degassing
the water to keep it crystal clear.

OK so bury the house and install large LED back lighted monitors in
place of windows - OR build a super thick concrete shell and add
monitors in place of windows.

Gives a whole new meaning to Windows PC. And moves people further
away from nature....

Find a house in the woods and commute.

 

[Jerry Avins]

On 9/17/2011 2:37 PM, Bret Cahill wrote:

The problem with noise canceling ear protection is...

... is that you've never owned a pair that work, and perhaps don't
understand the physic involved. Mine work beautifully.

Talking out of your ass is what you do best, worm.

Marvin, you appear to be just plain ignorant about so many things.
And so stubborn about educating yourself about the relevant science.

It's much worse than that. A "libertarian" cannot even apply the
most simple most basic logic to his [supposedly] most cherished
subject: freedom, free markets and free speech. For example, just
ask any "libertarian" The Question, "Does free speech precede each and
every free trade?" and he'll start dodging as though his life depended
upon it.

Expecting someone that dizzy and confused to apply even middle school
level math is a farce.

And it goes downhill from there.

You've been riding that hobby horse for quite a while now:
http://www.edaboard.co.uk/chip-with-simple-program-for-toy-t8894,start,8670.html

Jerry
--
Engineering is the art of making what you want from things you can get.

 

[whit3rd]

On Saturday, September 17, 2011 12:01:15 PM UTC-7, John Larkin wrote:

On Sat, 17 Sep 2011 11:38:07 -0700 (PDT), whit3rd <whi...@gmail.com
wrote:

On Friday, September 16, 2011 3:16:54 PM UTC-7, John Larkin wrote:
On Fri, 16 Sep 2011 13:37:49 -0700 (PDT), whit3rd <whi...@gmail.com
wrote:

For more on this subject, refer to Arthur Clarke's _Tales from the White Hart_,

Is that the story where the noise canceler exploded?

But consider: the power output of the device has to cancel sound,
thus reducing the energy in the room.

COE is part of the problem. If a transducer were somehow intelligent
enough to cancel the sound pressure at some usefully distant volume in
a room (unlikely, but take it as a hypothetical) it will be net
outputting sound.

No, not at all. One might cancel the fluctuations at a point by output of energy
but that merely creates a NODE of the soundwaves. If you cancel the sound
fluctuations in a room-sized or house-sized volume, that's equivalent
to salting the region with completely efficient energy-harvesters.
Just as a dynamic microphone grabs fleapower from the sound, the
hypothetical absorber would have an acoustic response that grabs
ALL (limited by thermodynamics, like Maxwell's demon) the energy.
Or, grabs all the energy until something goes nonlinear. *POP*

 

[krw@att.bizzzzzzzzzzzz]

On 17 Sep 2011 14:32:50 GMT, jmfbahciv <See.above@aol.com> wrote:

glen herrmannsfeldt wrote:
In comp.dsp CWatters <colin.watters@noturnersoakspam.plus.com> wrote:
On 15/09/2011 16:45, Bret Cahill wrote:

The system could monitor the location of the head of each person in
the room.

That's not the main problem.

The difficulty is getting the antinoise signal to the persons head
without it being audible at another persons head.

If you get the noise low at the walls, it should (on average) stay
low throughout the room. That can take a lot of microphones and
speakers, as the frequency increases.

In fact it's worse than that. Even when there is only one person, the
anti noise needed to suppress noise in one ear is a source of noise that
has to be suppressed in the other ear.

At some point, it is an N variables and N unknowns problem.
For N people in 3D, you have 3N variables, so you need at least 3N
speakers to select the phase for. (Well, maybe one less.) More
will get you larger, depending on wavelength, regions around the head.

Unless you figure out how to make sound waves incredibly directional
(for all frequencies) I can't see how it can be done.

If you have a whole wall of microphones outside, and speakers inside,
each adjusted with the appropriate delay (though the wall) and
amplitude (how much leaks through the wall that needs cancelling)
then, for wavelengths somewhat longer than the speaker spacing it
should pretty much cancel throughout the room.

But the other speaking person is part of that noise. If the OP
is a guy, can't he just use his selective hearing software? )))

There is a difference between selective hearing and selective *listening*. ;-)

 

[John Larkin]

On Sat, 17 Sep 2011 15:37:24 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Saturday, September 17, 2011 12:01:15 PM UTC-7, John Larkin wrote:
On Sat, 17 Sep 2011 11:38:07 -0700 (PDT), whit3rd <whi...@gmail.com
wrote:

On Friday, September 16, 2011 3:16:54 PM UTC-7, John Larkin wrote:
On Fri, 16 Sep 2011 13:37:49 -0700 (PDT), whit3rd <whi...@gmail.com
wrote:

For more on this subject, refer to Arthur Clarke's _Tales from the White Hart_,

Is that the story where the noise canceler exploded?

But consider: the power output of the device has to cancel sound,
thus reducing the energy in the room.

COE is part of the problem. If a transducer were somehow intelligent
enough to cancel the sound pressure at some usefully distant volume in
a room (unlikely, but take it as a hypothetical) it will be net
outputting sound.

No, not at all. One might cancel the fluctuations at a point by output of energy
but that merely creates a NODE of the soundwaves. If you cancel the sound
fluctuations in a room-sized or house-sized volume, that's equivalent
to salting the region with completely efficient energy-harvesters.

That's not what people usually think of as noise canceling. I think.

So you could make the outer wall of a house out of thousands of tiny
speakers, each with an optical interferometer or equivalent thing
sensing the cone position. Electronics would servo the cones to make
each be stationary with respect to the inner wall. That would make
each little cone essentially infinitely stiff. Since the cones don't
move, no sound gets past them. From outside the house, they look like
acoustic reflectors.

Concrete-filled cinder blocks might work, too.

John

 

[Bret Cahill]

There is some otherwise nice real estate at the end of Navy runways,
neighborhoods in San Diego and Virginia Beach where pilots practice
taking off an aircraft carrier with after burners wide open.

A lot of residents would be willing to pay $5,000 or more to be able
to talk to other people in a room at the flip of a switch. If it
draws a lot of power or when there is little outdoor noise it might be
desirable to turn it off or have it automatically turn off after 5
minutes and then back on as soon as the noise exceeds a threshold.

Noise cancellation should be cheaper than redoing the walls and in
some ways it might be an easier problem than headphones where the
distances involved are only a cm.

A few noisy zones might be tolerable as long as the locations of quiet
zones in a room could be moved and adjusted.

Maybe I missed it, but in all the proposals that have been
bandied about here, nobody seems to have suggested "simple"
servo systems:

Force balance accelerometers cost over a thousand dollars, F-B load
cells even more. Above they mentioned something about using speakers
as microphones and there may be some question as to if that is really
fundamentally different than servos.

Dealing for the moment only with noise that
gets into the house via transmission through the walls, we
can envision walls covered with active panels. Each uses a
servo system to hold a stationary position. If the interior
of the wall doesn't move, then no sound passes through it.

That might even be possible with glass or Plexiglas.

Of course, to handle high frequencies would require a *lot*
of small servo panels.

If you needed dozens or hundreds of something that expensive it might
be cheaper to just rebuild the house. A lot of these houses in Point
Loma and Seatack aren't all that big.

OK, I didn't say it would be *easy*. But maybe easier than
dealing with microphone arrays, speaker arrays, head
tracking, phase cancellation, etc, etc, etc.

Once we've dealt with wall transmission, we can deal with
windows. Suppose the window glass is gripped at the edges
(out of sight) by drivers that can apply bending forces.
They could also sense bending to derive the feedback signal,
but we'd probably need to supplement that with something
like an IR reflection scheme to pick up more central
motions.

If you are really good at PR you could spin all the coils and magnets
in the window pane as "postmodern architecture."

BTW, what's the hold up on clear conductors and magnets with a low
index of refraction? If you don't have some Law of Nature that states
transparent is impossible you have exactly thirty (30) days to
producing clear conductors and magnets.

Lastly, sound entry via ductwork is probably the easiest to
deal with. (As I recall, ducts were the first things to
have ANC applied successfully, decades before headphones.)

Of course, to power all these servos will require your own
electrical generation plant... noisy, but now we know how to
deal with that!

If there is _that_ much power in noise maybe there is some way to
extract it and use it to power LEDS or something.

Best regards,

Bob Masta

DAQARTA v6.02
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, FREE Signal Generator
Pitch Track, Pitch-to-MIDI
Science with your sound card!- Hide quoted text -

- Show quoted text -

 

[glen herrmannsfeldt]

In comp.dsp Bret Cahill <Bret_E_Cahill@yahoo.com> wrote:

(snip)

BTW, what's the hold up on clear conductors and magnets with a low
index of refraction? If you don't have some Law of Nature that states
transparent is impossible you have exactly thirty (30) days to
producing clear conductors and magnets.

Indium Tin Oxide is the favorite transparent conductor. It is
commonly used as heaters for grocery store freezer windows, so
that they don't frost up. Also, I believe for LCD displays.

Somewhat high resisitivity, but good enough for some cases.

-- glen

 

[whit3rd]

On Saturday, September 17, 2011 8:38:50 PM UTC-7, John Larkin wrote:

On Sat, 17 Sep 2011 15:37:24 -0700 (PDT), whit3rd <whi...@gmail.com
wrote:

... If you cancel the sound
fluctuations in a room-sized or house-sized volume, that's equivalent
to salting the region with completely efficient energy-harvesters.

That's not what people usually think of as noise canceling. I think.

So you could make the outer wall of a house out of thousands of tiny
speakers...
Concrete-filled cinder blocks might work, too.

Air velocity in a sound wave becomes zero at the surface of a concrete block
but again, that's only in ONE dimension, normal to the block's surface; the
block surface is an enforced node of one of the three velocity components
of the soundwave. Similarly, 'speaker' transducers can only cancel one of
the three components of impinging waves. So, neither approach will
replicate the idealized sci-fi gadget. Fog, though (because there's an
asymmetry in overpressure-condensation and underpressure-evaporation
on the water droplets) has possibilities.

 

[whit3rd]

On Saturday, September 17, 2011 8:11:57 PM UTC-7, Bret Cahill wrote:

BTW, what's the hold up on clear conductors and magnets with a low
index of refraction? If you don't have some Law of Nature that states
transparent is impossible you have exactly thirty (30) days to
producing clear conductors and magnets.

Oh, THAT law of nature: easy, the nature of light is electric and magnetic
wave, and our technology of magnetic materials involves very high
permeability, i.e. very high reflectivity to any impinging wave.
If the transparent conducting materials on your LCD display were
examined at low frequency, below their plasma freqency cutoff,
they'd be reflective or opaque. It's only visible light that gets a pass on those
transparent conductors (indium tin oxide, technically it's a semiconductor).

In terms of low-permeability magnetic materials, you might consider
liquid oxygen (hey, it's transparent!). Not ready for home use, though.

 

[Bret Cahill]

...  If you cancel the sound
fluctuations in a room-sized or house-sized volume, that's equivalent
to salting the region with completely efficient energy-harvesters.

That's not what people usually think of as noise canceling. I think.

So you could make the outer wall of a house out of thousands of tiny
speakers...
Concrete-filled cinder blocks might work, too.

Air velocity in a sound wave becomes zero at the surface of a concrete block
but again, that's only in ONE dimension, normal to the block's surface; the
block surface is an enforced node of one of the three velocity components
of the soundwave.   Similarly, 'speaker' transducers can only cancel one of
the three components of impinging waves.  So, neither approach will
replicate the idealized sci-fi gadget.   Fog, though (because there's an
asymmetry in overpressure-condensation and underpressure-evaporation
on the water droplets) has possibilities.

How is a servo panel held frozen in the normal direction going to
receive and transmit any components that are parallel to the panel?

The receiving edge is low profile creating little parallel movement
and the "broadcasting" edge reduces it even more.

The noise reduction in the directions parallel to one wall will take
place in the adjacent walls or ceiling.


Bret Cahill