Turn Your House Into Noise Cancellation Headphones

[tuinkabouter]

On 9/15/2011 1:04 AM, Bret Cahill wrote:

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.

Just buy a sam 7.

 

[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 residents are willing to pay that kind of cash to lower the
ambient noise levels in their homes then all they need to do
is soundproof them.  

But then you don't learn anything about new applications for
DSP technology.

Insulating the walls does just that and it also brings the added
benefit of reducing the energy spent in HVAC.  

San Diego has a pretty moderate climate, so HVAC cost should already
be pretty low.  Virginia Beach may be different.

Adding sound reflection panels also helps, with the added benefit
of being able to provide some shade.  None of these technologies
require an increase in energy spending.

The next problem is diffraction.  Sound reflection is fine, but
the low frequencies will diffract around the edge.  I will guess
that jet fighters with afterburners make a lot of low frequencies.
Low frequencies are also harder to absorb inside the walls.

Now, if someone proposed this as a research project it might be
that someone would fund it.  Use all the technologies: sound
reflection, sound absorption, and active cancelation in one house.

Since the Navy is creating the noise it could could start off paying
for some R & D for an aircraft control tower redo, either on land at
Oceana or N. Island or on a carrier.

Later on a commercial version w/o the chrome plating would appear.


Bret Cahill

 

[John Larkin]

On Wed, 14 Sep 2011 16:04:09 -0700 (PDT), Bret Cahill
<Bret_E_Cahill@yahoo.com> wrote:

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.


Bret Cahill

Won't work, probably physically impossible. Buy earplugs.

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.

Just buy a sam 7.

Gadaffy's are already on Ebay.

 

[Marvin the Martian]

On Thu, 15 Sep 2011 16:22:39 -0400, Jerry Avins wrote:

On 9/15/2011 2:02 PM, Marvin the Martian wrote:

...

You only need speakers that are spaced about 1/2 the highest wavelength
of the highest frequency you want to cancel.

Highest wavelength of the highest frequency?

I had a brain cramp, apparently.

At any one frequency, there
is only one wavelength. Did you mean, "wavelength of the highest
frequency"? Let's see: sound travels about 1100 ft/sec in air, and 10
KHz is a low end for decent cancellation. 1.1/10 gives a wavelength of
.11 ft, and half of that is .055 ft or .66 in. What qualifies as "only"?

And you don't form a beam (though you could...) you make it look like
the canceling sound is coming from the same point in space as the
noise.

Good trick! How?

Jerry

 

[Marvin the Martian]

On Thu, 15 Sep 2011 16:22:39 -0400, Jerry Avins wrote:

On 9/15/2011 2:02 PM, Marvin the Martian wrote:

...

You only need speakers that are spaced about 1/2 the highest wavelength
of the highest frequency you want to cancel.

Highest wavelength of the highest frequency? At any one frequency, there
is only one wavelength. Did you mean, "wavelength of the highest
frequency"? Let's see: sound travels about 1100 ft/sec in air, and 10
KHz is a low end for decent cancellation. 1.1/10 gives a wavelength of
.11 ft, and half of that is .055 ft or .66 in. What qualifies as "only"?

And you don't form a beam (though you could...) you make it look like
the canceling sound is coming from the same point in space as the
noise.

Good trick! How?

It's mostly math... I visited Sony once. They had a noise canceling box -
you stick your head in it. You could move your head around and you could
barely hear outside the box. It was a demonstration of how noise in an
area could be canceled using a Bessel array. That must have been almost
20 years ago, and the box wasn't public at the time then. I've not kept
up on the subject so I don't know if they pressed on with the subject.
Like I said, I was replaced by a sexy blond bimbo with big tits who was
sucking up on management.

 

[John Larkin]

On Fri, 16 Sep 2011 01:47:11 +0000 (UTC), glen herrmannsfeldt
<gah@ugcs.caltech.edu> wrote:

In comp.dsp John Larkin <jjlarkin@highnotlandthistechnologypart.com> wrote:

(snip, someone wrote)
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.

(snip)
Won't work, probably physically impossible. Buy earplugs.

I probably would have said that before hearing (or not) noise
canceling headphones. In this case, if you put the microphones
outside and the speakers inside, and have a reasonable noise
reduction due to insulation, there should be very little feedback
from the speaker to the microphone. I believe that isn't so true
for the headphones, though they still seem to work.

To do it well, though, would take a LOT of speakers and microphones.

Maybe one per square meter of wall and ceiling area. (You get
a quantity discount on the parts.) Calibration would also be
interesting.

With enough DSP, maybe you could get away with fewer microphones,
but still with many speakers, by doing some correlation and delay,
and with the assumption that the sound mostly comes from one,
or a small number of, directions.

-- glen

Well, let me know when you get it working.

John

 

[glen herrmannsfeldt]

In comp.dsp John Larkin <jjlarkin@highnotlandthistechnologypart.com> wrote:

(snip, someone wrote)

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.

(snip)

Won't work, probably physically impossible. Buy earplugs.

I probably would have said that before hearing (or not) noise
canceling headphones. In this case, if you put the microphones
outside and the speakers inside, and have a reasonable noise
reduction due to insulation, there should be very little feedback
from the speaker to the microphone. I believe that isn't so true
for the headphones, though they still seem to work.

To do it well, though, would take a LOT of speakers and microphones.

Maybe one per square meter of wall and ceiling area. (You get
a quantity discount on the parts.) Calibration would also be
interesting.

With enough DSP, maybe you could get away with fewer microphones,
but still with many speakers, by doing some correlation and delay,
and with the assumption that the sound mostly comes from one,
or a small number of, directions.

-- glen

 

[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.

Bret Cahill

Won't work, probably physically impossible.

Most of the noise is below 1 - 2 k Hz

http://www.nasa.gov/centers/dryden/pdf/87814main_H-685.pdf

Buy earplugs.

If you want to talk at dinner you'll need a walkie talkie version of
noise cancellation headphones.

But then you'd get spaghetti sauce all over the mike . . .


Bret Cahill

 

[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.  

(snip)

Won't work, probably physically impossible. Buy earplugs.

I probably would have said that before hearing (or not) noise
canceling headphones.  In this case, if you put the microphones
outside and the speakers inside, and have a reasonable noise
reduction due to insulation, there should be very little feedback
from the speaker to the microphone.  I believe that isn't so true
for the headphones, though they still seem to work.

To do it well, though, would take a LOT of speakers and microphones.

There may be some short cuts.

Maybe one per square meter of wall and ceiling area.  (You get
a quantity discount on the parts.)  Calibration would also be
interesting.  

With enough DSP, maybe you could get away with fewer microphones,
but still with many speakers, by doing some correlation and delay,
and with the assumption that the sound mostly comes from one,
or a small number of, directions.

It may be a challenging project.


Bret Cahill

 

[Sam Wormley]

On 9/16/11 12:13 AM, Kaz Kylheku wrote:

Also, noise canceling headphones largely do not work.

Why do you say that noise canceling headphones largely do not work?

 

[Kaz Kylheku]

On 2011-09-15, Peter Webb <webbfamily@optusnetDIESPAMDIE.com.au> wrote:

Noise cancelling headphones largely work because:

Also, noise canceling headphones largely do not work.

 

[CWatters]

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.

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.

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

 

[Robert Adams]

On Sep 15, 11:01 pm, Marvin the Martian <mar...@ontomars.org> wrote:

On Thu, 15 Sep 2011 16:22:39 -0400, Jerry Avins wrote:
On 9/15/2011 2:02 PM, Marvin the Martian wrote:

   ...

You only need speakers that are spaced about 1/2 the highest wavelength
of the highest frequency you want to cancel.

Highest wavelength of the highest frequency?

I had a brain cramp, apparently.



At any one frequency, there
is only one wavelength. Did you mean, "wavelength of the highest
frequency"? Let's see: sound travels about 1100 ft/sec in air, and 10
KHz is a low end for decent cancellation. 1.1/10 gives a wavelength of
.11 ft, and half of that is .055 ft or .66 in. What qualifies as "only"?

And you don't form a beam (though you could...) you make it look like
the canceling sound is coming from the same point in space as the
noise.

Good trick! How?

Jerry- Hide quoted text -

- Show quoted text -

The dream of producing a large area of cancellation in an open space
inside a house is probably not practical at this time, and has been a
pipe dream for the last 50 years. A lot of work is going into making
cars into a noise-cancelled zone, with some sucess, but these systems
work by having multiple microphones picking up all the various sources
of noise (engine compartment, tires, etc) together with microphones in
the headrest that are quite close to your ears that are representitive
of what you are hearing. Note that in the car case you would be quite
happy with noise cancellation extending up to 100 Hz or so, since the
noise is so dominated by the low frequencies, so the wavelengths are
quite large and therefore microphones in the headrest are getting a
good representation of the sound pressure at your ear. This technique
does not generalize well to a house situation.


I know someone with a deep background in physics who is experimenting
with "meta-materials" that have a negative modulus, and he claims that
you can cause a wave to bend "around" an object. So far there is no
way to do this for a broadband audio signal, but there are some
results for narrowband ultrasonic materials

http://www.nature.com/nmat/journal/v5/n6/full/nmat1644.html

Note that almost all noise-cancelling headphones are feedback systems,
not feed-foward as described in this thread.

One solution to using feedback noise-cancellation over larger
distances is to fill your entire house with Hydrogen, which speeds up
the velocity of sound. You might experience a few seconds a blissfull
noise-cancelled silence before you either suffocate or explode. In
either case you will no longer be bothered by outside noises.

 

[HardySpicer]

On Sep 15, 11:04 am, Bret Cahill <Bret_E_Cah...@yahoo.com> wrote:

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.

Bret Cahill

Reminds me of the saying after the movie "Raise the Titanic"

Raise the titanic? It would have been cheaper to lower the Atlantic!

Hardy

 

[Rui Maciel]

Bret Cahill wrote:

This was for a normal looking house, large glass windows, etc. The
cheapest passive way to reduce the low frequency noise from an
afterburner 150' above to a level that allows conversation is to dig a
bunker which is difficult to keep submerged in Va. Beach.

Have you actually made the relevant cost analysis or did you just made this
up?

Also a lot of people rent their homes. They can always sell the
system when they move.

If a landlord soundproofs their home then the ambient noise level is reduced
for whoever rents the place. If someone rents a place which doesn't have
adequate sound insulation and is placed next to an air base then basically
all that person is able to do is to complain that he rented a terrible home
which is poorly build and badly located. No amount of noise cancellation
devices will fix this.

Insulating the walls does just that and it also brings the added benefit
of reducing the energy spent in HVAC. Adding sound reflection panels
also helps, with the added benefit of being able to provide some shade.
None of these technologies require an increase in energy spending.

The father of a concert symphony music composer worked on noise
reduction at NASA. He never was successful according to his kid.

You make it sound like there is no such thing as an anechoic chamber.


Rui Maciel

 

[Rui Maciel]

Bret Cahill wrote:

The system could monitor the location of the head of each person in
the room. GPS isn't quite there yet so it must be done locally, with
sonar or radar using a target much less cumbersome than headphones,
i.e., an ear ring, cap or necklace.

The signals from the speakers would be coordinated to eliminate just
the noise in a small 0.03 m^3 volume around each head.

This approach requires a more sophistication in the design but would
greatly reduce the cost and power and the number and/or size of the
speakers for the production run.

If you actually consider placing GPS devices in people's heads, install
radar head-trackers or necklace tracking devices just to be able to talk to
someone in the same room then you should seriously consider moving to a
different home.


Rui Maciel

 

[Michael A. Terrell]

Sam Wormley wrote:

On 9/16/11 12:13 AM, Kaz Kylheku wrote:

Also, noise canceling headphones largely do not work.

Why do you say that noise canceling headphones largely do not work?

Do you have the owner's manual, or have you asked the manufacturer or
company you got it from?

Have you looked online for that brand & model, which you failed to
mention?


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

 

On Thu, 15 Sep 2011 02:03:56 +0000 (UTC), glen herrmannsfeldt
<gah@ugcs.caltech.edu> wrote:

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

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.

I have heard of using triple pane windows to reduce noise near
freeways. That might not be enough for jet fighters, though.

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.

But the (wall) area is larger. I believe that takes drivers
(speakers) distributed along the walls, spaced depending on
the frequencies that need canceling and the amount of cancelation
required. But $5000 is a small part of the price of most houses,
so you could probably go somewhat more.

And, you could also use it as a sound system at the same time!

Extra DSP challenge, it has to send the right signal to each speaker
such that a reasonable stereo image is formed.

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

Have a computer follow each person around and adjust the cancelation
for those positions in the room where people are.

I have also heard about active concert hall reflection control
systems that make halls that are acoustically larger than the
actual size, or otherwise improve the acoustics. It seems that
the problems could be related.


-- glen

Why does everyone get all holy about "digital signal processing?"
Wouldn't something like this be better handled with analog
electronics?

And a whole lot of yet-to-be-invented expensive wall-sized planar
acoustic drivers.

But I guess if it was easy, someone would have done it already.

Thinking about the challenge, triple pane glass, 2X6 plates, staggered
studs, and heavy insulation make more sense. Saves on heating and
cooling too.

 

[jmfbahciv]

John Larkin wrote:

On Fri, 16 Sep 2011 01:47:11 +0000 (UTC), glen herrmannsfeldt
gah@ugcs.caltech.edu> wrote:

In comp.dsp John Larkin <jjlarkin@highnotlandthistechnologypart.com> wrote:

(snip, someone wrote)
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.

(snip)
Won't work, probably physically impossible. Buy earplugs.

I probably would have said that before hearing (or not) noise
canceling headphones. In this case, if you put the microphones
outside and the speakers inside, and have a reasonable noise
reduction due to insulation, there should be very little feedback
from the speaker to the microphone. I believe that isn't so true
for the headphones, though they still seem to work.

To do it well, though, would take a LOT of speakers and microphones.

Maybe one per square meter of wall and ceiling area. (You get
a quantity discount on the parts.) Calibration would also be
interesting.

With enough DSP, maybe you could get away with fewer microphones,
but still with many speakers, by doing some correlation and delay,
and with the assumption that the sound mostly comes from one,
or a small number of, directions.

-- glen

Well, let me know when you get it working.

Just making the refrigerators shut up would be helpful.

/BAH