Hi,

I live about 100 yards from a major highway, and despite a noise
abatement wall have a significant noise level in my backyard. The
back of my house faces the highway, although there are two intervening
houses, a sidestreet, and the noise abatement wall. The noise is not
deafening, but is unpleasant.

I am thinking of constructing a screened-in porch adjacent to my house
in the backyard, but would be more inclined to do so if I could figure
out a way to reduce the noise level for those sitting inside the
porch.

I was thinking of directing two or three directional microphones on
the outside edge of the porch, towards the highway. I would then use
active noise cancellation to create a more pleasant environment for
those sitting on the porch.

My questions a
1. is this feasible? Will it work better with music playing (i.e., by
subtraction) or by attempting to add missing frequencies?
2. can this best be done using solely audio components, or best done
by computer?
3. if done by computer, which algorithms are appropriate? Psuedocode
would be welcome.

I have access to Matlab, at least for purposes of building a
prototype.

TIA,

Jonathan

On 17 Mar 2004 05:21:35 -0800, (Jonathan
Epstein) wrote:

Hi,

I live about 100 yards from a major highway, and despite a noise
abatement wall have a significant noise level in my backyard. The
back of my house faces the highway, although there are two intervening
houses, a sidestreet, and the noise abatement wall. The noise is not
deafening, but is unpleasant.

I am thinking of constructing a screened-in porch adjacent to my house
in the backyard, but would be more inclined to do so if I could figure
out a way to reduce the noise level for those sitting inside the
porch.

I was thinking of directing two or three directional microphones on
the outside edge of the porch, towards the highway. I would then use
active noise cancellation to create a more pleasant environment for
those sitting on the porch.

My questions a
1. is this feasible? Will it work better with music playing (i.e., by
subtraction) or by attempting to add missing frequencies?
2. can this best be done using solely audio components, or best done
by computer?
3. if done by computer, which algorithms are appropriate? Psuedocode
would be welcome.

I have access to Matlab, at least for purposes of building a
prototype.

TIA,

Jonathan

A decent level of noise reduction can only be achieved in an area
bounded by sides considerably less than one wavelength. If you examine
your yard and the kind of noises you are trying to suppress, you will
unfortunately find that this project is a non-starter.

d

_____________________________

http://www.pearce.uk.com

On 17 Mar 2004 05:21:35 -0800, (Jonathan
Epstein) wrote:

Hi,

I live about 100 yards from a major highway, and despite a noise
abatement wall have a significant noise level in my backyard. The
back of my house faces the highway, although there are two intervening
houses, a sidestreet, and the noise abatement wall. The noise is not
deafening, but is unpleasant.

I am thinking of constructing a screened-in porch adjacent to my house
in the backyard, but would be more inclined to do so if I could figure
out a way to reduce the noise level for those sitting inside the
porch.

I was thinking of directing two or three directional microphones on
the outside edge of the porch, towards the highway. I would then use
active noise cancellation to create a more pleasant environment for
those sitting on the porch.

My questions a
1. is this feasible? Will it work better with music playing (i.e., by
subtraction) or by attempting to add missing frequencies?
2. can this best be done using solely audio components, or best done
by computer?
3. if done by computer, which algorithms are appropriate? Psuedocode
would be welcome.

I have access to Matlab, at least for purposes of building a
prototype.

TIA,

Jonathan

A decent level of noise reduction can only be achieved in an area
bounded by sides considerably less than one wavelength. If you examine
your yard and the kind of noises you are trying to suppress, you will
unfortunately find that this project is a non-starter.

d

_____________________________

http://www.pearce.uk.com

On 17 Mar 2004 05:21:35 -0800, (Jonathan
Epstein) wrote:

Hi,

I live about 100 yards from a major highway, and despite a noise
abatement wall have a significant noise level in my backyard. The
back of my house faces the highway, although there are two intervening
houses, a sidestreet, and the noise abatement wall. The noise is not
deafening, but is unpleasant.

I am thinking of constructing a screened-in porch adjacent to my house
in the backyard, but would be more inclined to do so if I could figure
out a way to reduce the noise level for those sitting inside the
porch.

I was thinking of directing two or three directional microphones on
the outside edge of the porch, towards the highway. I would then use
active noise cancellation to create a more pleasant environment for
those sitting on the porch.

My questions a
1. is this feasible? Will it work better with music playing (i.e., by
subtraction) or by attempting to add missing frequencies?
2. can this best be done using solely audio components, or best done
by computer?
3. if done by computer, which algorithms are appropriate? Psuedocode
would be welcome.

I have access to Matlab, at least for purposes of building a
prototype.

TIA,

Jonathan

A decent level of noise reduction can only be achieved in an area
bounded by sides considerably less than one wavelength. If you examine
your yard and the kind of noises you are trying to suppress, you will
unfortunately find that this project is a non-starter.

d

_____________________________

http://www.pearce.uk.com

On 17 Mar 2004 05:21:35 -0800, (Jonathan
Epstein) wrote:

Hi,

I live about 100 yards from a major highway, and despite a noise
abatement wall have a significant noise level in my backyard. The
back of my house faces the highway, although there are two intervening
houses, a sidestreet, and the noise abatement wall. The noise is not
deafening, but is unpleasant.

I am thinking of constructing a screened-in porch adjacent to my house
in the backyard, but would be more inclined to do so if I could figure
out a way to reduce the noise level for those sitting inside the
porch.

I was thinking of directing two or three directional microphones on
the outside edge of the porch, towards the highway. I would then use
active noise cancellation to create a more pleasant environment for
those sitting on the porch.

My questions a
1. is this feasible? Will it work better with music playing (i.e., by
subtraction) or by attempting to add missing frequencies?
2. can this best be done using solely audio components, or best done
by computer?
3. if done by computer, which algorithms are appropriate? Psuedocode
would be welcome.

I have access to Matlab, at least for purposes of building a
prototype.

TIA,

Jonathan

A decent level of noise reduction can only be achieved in an area
bounded by sides considerably less than one wavelength. If you examine
your yard and the kind of noises you are trying to suppress, you will
unfortunately find that this project is a non-starter.

d

_____________________________

http://www.pearce.uk.com

Jonathan Epstein wrote:

I am thinking of constructing a screened-in porch adjacent to my house
in the backyard, but would be more inclined to do so if I could figure
out a way to reduce the noise level for those sitting inside the
porch.

The screening should be a solid wall, palte glass being a good
possibility, contiguous and inclosing on at least three sides the area
in which you expect to spend the majority of your time. That screen
barrier should be at least 6' to 8' (1.8 to 2.4m) high. Your
sitting-talking table should be as close as possible to that wall, the
traffic noise of course impinging the other side.

Angelo Campanella
--
--------- www.CampanellaAcoustics.com ---------

"I have simply studied carefully whatever I've undertaken, and tried to
hold a reserve that would carry me through." - Charles A. Lindbergh.

"As for background noise level; 35 dBA is a good classroom; 45 dBA is a
sound masking system!" - Anthony K. Hoover

Jonathan Epstein wrote:

I am thinking of constructing a screened-in porch adjacent to my house
in the backyard, but would be more inclined to do so if I could figure
out a way to reduce the noise level for those sitting inside the
porch.

The screening should be a solid wall, palte glass being a good
possibility, contiguous and inclosing on at least three sides the area
in which you expect to spend the majority of your time. That screen
barrier should be at least 6' to 8' (1.8 to 2.4m) high. Your
sitting-talking table should be as close as possible to that wall, the
traffic noise of course impinging the other side.

Angelo Campanella
--
--------- www.CampanellaAcoustics.com ---------

"I have simply studied carefully whatever I've undertaken, and tried to
hold a reserve that would carry me through." - Charles A. Lindbergh.

"As for background noise level; 35 dBA is a good classroom; 45 dBA is a
sound masking system!" - Anthony K. Hoover

Jonathan Epstein wrote:

I am thinking of constructing a screened-in porch adjacent to my house
in the backyard, but would be more inclined to do so if I could figure
out a way to reduce the noise level for those sitting inside the
porch.

The screening should be a solid wall, palte glass being a good
possibility, contiguous and inclosing on at least three sides the area
in which you expect to spend the majority of your time. That screen
barrier should be at least 6' to 8' (1.8 to 2.4m) high. Your
sitting-talking table should be as close as possible to that wall, the
traffic noise of course impinging the other side.

Angelo Campanella
--
--------- www.CampanellaAcoustics.com ---------

"I have simply studied carefully whatever I've undertaken, and tried to
hold a reserve that would carry me through." - Charles A. Lindbergh.

"As for background noise level; 35 dBA is a good classroom; 45 dBA is a
sound masking system!" - Anthony K. Hoover

Jonathan Epstein wrote:

I am thinking of constructing a screened-in porch adjacent to my house
in the backyard, but would be more inclined to do so if I could figure
out a way to reduce the noise level for those sitting inside the
porch.

The screening should be a solid wall, palte glass being a good
possibility, contiguous and inclosing on at least three sides the area
in which you expect to spend the majority of your time. That screen
barrier should be at least 6' to 8' (1.8 to 2.4m) high. Your
sitting-talking table should be as close as possible to that wall, the
traffic noise of course impinging the other side.

Angelo Campanella
--
--------- www.CampanellaAcoustics.com ---------

"I have simply studied carefully whatever I've undertaken, and tried to
hold a reserve that would carry me through." - Charles A. Lindbergh.

"As for background noise level; 35 dBA is a good classroom; 45 dBA is a
sound masking system!" - Anthony K. Hoover

"Jonathan Epstein" wrote in message
om...
Hi,

I live about 100 yards from a major highway, and despite a noise
abatement wall have a significant noise level in my backyard. The
back of my house faces the highway, although there are two
intervening
houses, a sidestreet, and the noise abatement wall. The noise is
not
deafening, but is unpleasant.

I am thinking of constructing a screened-in porch adjacent to my
house
in the backyard, but would be more inclined to do so if I could
figure
out a way to reduce the noise level for those sitting inside the
porch.

I was thinking of directing two or three directional microphones on
the outside edge of the porch, towards the highway. I would then
use
active noise cancellation to create a more pleasant environment for
those sitting on the porch.

My questions a
1. is this feasible? Will it work better with music playing (i.e.,
by
subtraction) or by attempting to add missing frequencies?
2. can this best be done using solely audio components, or best done
by computer?
3. if done by computer, which algorithms are appropriate?
Psuedocode
would be welcome.

I have access to Matlab, at least for purposes of building a
prototype.

TIA,

Jonathan

Hello Jonathan

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does, but
this time refocusing the sound energy back away from the house, sorta
like a sound mirror.
your probably need planning permission as im guessing its gona be very
large and it may look a bit industrial but it's maybe worth a
thought. And its passive ! you could then use the anti-phase-sound
idea to clear up the rest although it's effect will diminish on a
square law from the loudspeakers.
That's my 2 pence worth.
Chris.

"Jonathan Epstein" wrote in message
om...
Hi,

I live about 100 yards from a major highway, and despite a noise
abatement wall have a significant noise level in my backyard. The
back of my house faces the highway, although there are two
intervening
houses, a sidestreet, and the noise abatement wall. The noise is
not
deafening, but is unpleasant.

I am thinking of constructing a screened-in porch adjacent to my
house
in the backyard, but would be more inclined to do so if I could
figure
out a way to reduce the noise level for those sitting inside the
porch.

I was thinking of directing two or three directional microphones on
the outside edge of the porch, towards the highway. I would then
use
active noise cancellation to create a more pleasant environment for
those sitting on the porch.

My questions a
1. is this feasible? Will it work better with music playing (i.e.,
by
subtraction) or by attempting to add missing frequencies?
2. can this best be done using solely audio components, or best done
by computer?
3. if done by computer, which algorithms are appropriate?
Psuedocode
would be welcome.

I have access to Matlab, at least for purposes of building a
prototype.

TIA,

Jonathan

Hello Jonathan

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does, but
this time refocusing the sound energy back away from the house, sorta
like a sound mirror.
your probably need planning permission as im guessing its gona be very
large and it may look a bit industrial but it's maybe worth a
thought. And its passive ! you could then use the anti-phase-sound
idea to clear up the rest although it's effect will diminish on a
square law from the loudspeakers.
That's my 2 pence worth.
Chris.

"Jonathan Epstein" wrote in message
om...
Hi,

I live about 100 yards from a major highway, and despite a noise
abatement wall have a significant noise level in my backyard. The
back of my house faces the highway, although there are two
intervening
houses, a sidestreet, and the noise abatement wall. The noise is
not
deafening, but is unpleasant.

I am thinking of constructing a screened-in porch adjacent to my
house
in the backyard, but would be more inclined to do so if I could
figure
out a way to reduce the noise level for those sitting inside the
porch.

I was thinking of directing two or three directional microphones on
the outside edge of the porch, towards the highway. I would then
use
active noise cancellation to create a more pleasant environment for
those sitting on the porch.

My questions a
1. is this feasible? Will it work better with music playing (i.e.,
by
subtraction) or by attempting to add missing frequencies?
2. can this best be done using solely audio components, or best done
by computer?
3. if done by computer, which algorithms are appropriate?
Psuedocode
would be welcome.

I have access to Matlab, at least for purposes of building a
prototype.

TIA,

Jonathan

Hello Jonathan

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does, but
this time refocusing the sound energy back away from the house, sorta
like a sound mirror.
your probably need planning permission as im guessing its gona be very
large and it may look a bit industrial but it's maybe worth a
thought. And its passive ! you could then use the anti-phase-sound
idea to clear up the rest although it's effect will diminish on a
square law from the loudspeakers.
That's my 2 pence worth.
Chris.

"Jonathan Epstein" wrote in message
om...
Hi,

I live about 100 yards from a major highway, and despite a noise
abatement wall have a significant noise level in my backyard. The
back of my house faces the highway, although there are two
intervening
houses, a sidestreet, and the noise abatement wall. The noise is
not
deafening, but is unpleasant.

I am thinking of constructing a screened-in porch adjacent to my
house
in the backyard, but would be more inclined to do so if I could
figure
out a way to reduce the noise level for those sitting inside the
porch.

I was thinking of directing two or three directional microphones on
the outside edge of the porch, towards the highway. I would then
use
active noise cancellation to create a more pleasant environment for
those sitting on the porch.

My questions a
1. is this feasible? Will it work better with music playing (i.e.,
by
subtraction) or by attempting to add missing frequencies?
2. can this best be done using solely audio components, or best done
by computer?
3. if done by computer, which algorithms are appropriate?
Psuedocode
would be welcome.

I have access to Matlab, at least for purposes of building a
prototype.

TIA,

Jonathan

Hello Jonathan

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does, but
this time refocusing the sound energy back away from the house, sorta
like a sound mirror.
your probably need planning permission as im guessing its gona be very
large and it may look a bit industrial but it's maybe worth a
thought. And its passive ! you could then use the anti-phase-sound
idea to clear up the rest although it's effect will diminish on a
square law from the loudspeakers.
That's my 2 pence worth.
Chris.

"chris" wrote in message
...

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does, but
this time refocusing the sound energy back away from the house, sorta
like a sound mirror.
That's my 2 pence worth.
Chris.



A basic barrier will block the direct sound and reflect it away. However,
you still have to recognize the significant amount of sound that could come
over the top and around the sides of a barrier.

"chris" wrote in message
...

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does, but
this time refocusing the sound energy back away from the house, sorta
like a sound mirror.
That's my 2 pence worth.
Chris.



A basic barrier will block the direct sound and reflect it away. However,
you still have to recognize the significant amount of sound that could come
over the top and around the sides of a barrier.

"chris" wrote in message
...

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does, but
this time refocusing the sound energy back away from the house, sorta
like a sound mirror.
That's my 2 pence worth.
Chris.



A basic barrier will block the direct sound and reflect it away. However,
you still have to recognize the significant amount of sound that could come
over the top and around the sides of a barrier.

"chris" wrote in message
...

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does, but
this time refocusing the sound energy back away from the house, sorta
like a sound mirror.
That's my 2 pence worth.
Chris.



A basic barrier will block the direct sound and reflect it away. However,
you still have to recognize the significant amount of sound that could come
over the top and around the sides of a barrier.

On Sat, 20 Mar 2004 12:40:55 -0000, "chris"
wrote:

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does, but
this time refocusing the sound energy back away from the house, sorta
like a sound mirror.
[snip]

That's been tried. In the late 60s or early 70s, a barrier with
narrow wedge shaped gaps was proposed. It was dubbed "Thnadner,"
after a character in a Dr. Seuss story. It did not work. Because the
sources were moving, the sought-after interference pattern kept
changing, washing out whatever theoretical/hypothetical benefit was
sought.

There was also the "Kinematic noise barrier," made of vertical
triangular slotted channels. It was utter bull, and the measurements
claiming that it worked were laughable. That was the only barrier
construction that the Federal Highway Administration specifically
declared they would never fund.

Active control of an outdoor area is possible, and has been
demonstrated for jet aircraft runup noise. Active control requires
knowing the source with enough lead time (and/or predictability) to
generate the control sound. The problem with active control of
highway noise is that you have multiple sources, all moving and
uncorrelated with each other. Handling that is beyond anything that
can be done today.

Ken Plotkin

On Sat, 20 Mar 2004 12:40:55 -0000, "chris"
wrote:

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does, but
this time refocusing the sound energy back away from the house, sorta
like a sound mirror.
[snip]

That's been tried. In the late 60s or early 70s, a barrier with
narrow wedge shaped gaps was proposed. It was dubbed "Thnadner,"
after a character in a Dr. Seuss story. It did not work. Because the
sources were moving, the sought-after interference pattern kept
changing, washing out whatever theoretical/hypothetical benefit was
sought.

There was also the "Kinematic noise barrier," made of vertical
triangular slotted channels. It was utter bull, and the measurements
claiming that it worked were laughable. That was the only barrier
construction that the Federal Highway Administration specifically
declared they would never fund.

Active control of an outdoor area is possible, and has been
demonstrated for jet aircraft runup noise. Active control requires
knowing the source with enough lead time (and/or predictability) to
generate the control sound. The problem with active control of
highway noise is that you have multiple sources, all moving and
uncorrelated with each other. Handling that is beyond anything that
can be done today.

Ken Plotkin

On Sat, 20 Mar 2004 12:40:55 -0000, "chris"
wrote:

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does, but
this time refocusing the sound energy back away from the house, sorta
like a sound mirror.
[snip]

That's been tried. In the late 60s or early 70s, a barrier with
narrow wedge shaped gaps was proposed. It was dubbed "Thnadner,"
after a character in a Dr. Seuss story. It did not work. Because the
sources were moving, the sought-after interference pattern kept
changing, washing out whatever theoretical/hypothetical benefit was
sought.

There was also the "Kinematic noise barrier," made of vertical
triangular slotted channels. It was utter bull, and the measurements
claiming that it worked were laughable. That was the only barrier
construction that the Federal Highway Administration specifically
declared they would never fund.

Active control of an outdoor area is possible, and has been
demonstrated for jet aircraft runup noise. Active control requires
knowing the source with enough lead time (and/or predictability) to
generate the control sound. The problem with active control of
highway noise is that you have multiple sources, all moving and
uncorrelated with each other. Handling that is beyond anything that
can be done today.

Ken Plotkin

On Sat, 20 Mar 2004 12:40:55 -0000, "chris"
wrote:

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does, but
this time refocusing the sound energy back away from the house, sorta
like a sound mirror.
[snip]

That's been tried. In the late 60s or early 70s, a barrier with
narrow wedge shaped gaps was proposed. It was dubbed "Thnadner,"
after a character in a Dr. Seuss story. It did not work. Because the
sources were moving, the sought-after interference pattern kept
changing, washing out whatever theoretical/hypothetical benefit was
sought.

There was also the "Kinematic noise barrier," made of vertical
triangular slotted channels. It was utter bull, and the measurements
claiming that it worked were laughable. That was the only barrier
construction that the Federal Highway Administration specifically
declared they would never fund.

Active control of an outdoor area is possible, and has been
demonstrated for jet aircraft runup noise. Active control requires
knowing the source with enough lead time (and/or predictability) to
generate the control sound. The problem with active control of
highway noise is that you have multiple sources, all moving and
uncorrelated with each other. Handling that is beyond anything that
can be done today.

Ken Plotkin

"Ken Plotkin" wrote in message
...
On Sat, 20 Mar 2004 12:40:55 -0000, "chris"
wrote:

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does,
but
this time refocusing the sound energy back away from the house,
sorta
like a sound mirror.
[snip]

That's been tried. In the late 60s or early 70s, a barrier with
narrow wedge shaped gaps was proposed. It was dubbed "Thnadner,"
after a character in a Dr. Seuss story. It did not work. Because
the
sources were moving, the sought-after interference pattern kept
changing, washing out whatever theoretical/hypothetical benefit was
sought.

There was also the "Kinematic noise barrier," made of vertical
triangular slotted channels. It was utter bull, and the
measurements
claiming that it worked were laughable. That was the only barrier
construction that the Federal Highway Administration specifically
declared they would never fund.

Active control of an outdoor area is possible, and has been
demonstrated for jet aircraft runup noise. Active control requires
knowing the source with enough lead time (and/or predictability) to
generate the control sound. The problem with active control of
highway noise is that you have multiple sources, all moving and
uncorrelated with each other. Handling that is beyond anything that
can be done today.

Ken Plotkin

Hello Ken
thanks for the info it's nice to know someone else had tried these
idea's (it was just conjecture on my part).
I can also see the problems you mention, guess this is why there's
never been a solution (the patent would be worth a fortune).
Suppose the best think might be for him to plant some tree's at least
they will look better, and the leave rustling may mash the traffic
noise.
Although I think it was Audi or Mercedes that used the technology
inside the car to reduce road and traffic noise..

"Ken Plotkin" wrote in message
...
On Sat, 20 Mar 2004 12:40:55 -0000, "chris"
wrote:

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does,
but
this time refocusing the sound energy back away from the house,
sorta
like a sound mirror.
[snip]

That's been tried. In the late 60s or early 70s, a barrier with
narrow wedge shaped gaps was proposed. It was dubbed "Thnadner,"
after a character in a Dr. Seuss story. It did not work. Because
the
sources were moving, the sought-after interference pattern kept
changing, washing out whatever theoretical/hypothetical benefit was
sought.

There was also the "Kinematic noise barrier," made of vertical
triangular slotted channels. It was utter bull, and the
measurements
claiming that it worked were laughable. That was the only barrier
construction that the Federal Highway Administration specifically
declared they would never fund.

Active control of an outdoor area is possible, and has been
demonstrated for jet aircraft runup noise. Active control requires
knowing the source with enough lead time (and/or predictability) to
generate the control sound. The problem with active control of
highway noise is that you have multiple sources, all moving and
uncorrelated with each other. Handling that is beyond anything that
can be done today.

Ken Plotkin

Hello Ken
thanks for the info it's nice to know someone else had tried these
idea's (it was just conjecture on my part).
I can also see the problems you mention, guess this is why there's
never been a solution (the patent would be worth a fortune).
Suppose the best think might be for him to plant some tree's at least
they will look better, and the leave rustling may mash the traffic
noise.
Although I think it was Audi or Mercedes that used the technology
inside the car to reduce road and traffic noise..

"Ken Plotkin" wrote in message
...
On Sat, 20 Mar 2004 12:40:55 -0000, "chris"
wrote:

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does,
but
this time refocusing the sound energy back away from the house,
sorta
like a sound mirror.
[snip]

That's been tried. In the late 60s or early 70s, a barrier with
narrow wedge shaped gaps was proposed. It was dubbed "Thnadner,"
after a character in a Dr. Seuss story. It did not work. Because
the
sources were moving, the sought-after interference pattern kept
changing, washing out whatever theoretical/hypothetical benefit was
sought.

There was also the "Kinematic noise barrier," made of vertical
triangular slotted channels. It was utter bull, and the
measurements
claiming that it worked were laughable. That was the only barrier
construction that the Federal Highway Administration specifically
declared they would never fund.

Active control of an outdoor area is possible, and has been
demonstrated for jet aircraft runup noise. Active control requires
knowing the source with enough lead time (and/or predictability) to
generate the control sound. The problem with active control of
highway noise is that you have multiple sources, all moving and
uncorrelated with each other. Handling that is beyond anything that
can be done today.

Ken Plotkin

Hello Ken
thanks for the info it's nice to know someone else had tried these
idea's (it was just conjecture on my part).
I can also see the problems you mention, guess this is why there's
never been a solution (the patent would be worth a fortune).
Suppose the best think might be for him to plant some tree's at least
they will look better, and the leave rustling may mash the traffic
noise.
Although I think it was Audi or Mercedes that used the technology
inside the car to reduce road and traffic noise..

"Ken Plotkin" wrote in message
...
On Sat, 20 Mar 2004 12:40:55 -0000, "chris"
wrote:

I'm no expert at this funny acoustics stuff, but I though it might
also be possible to construct a high fence with the correct gapping
between the verticals such that it would act as a room lens does,
but
this time refocusing the sound energy back away from the house,
sorta
like a sound mirror.
[snip]

That's been tried. In the late 60s or early 70s, a barrier with
narrow wedge shaped gaps was proposed. It was dubbed "Thnadner,"
after a character in a Dr. Seuss story. It did not work. Because
the
sources were moving, the sought-after interference pattern kept
changing, washing out whatever theoretical/hypothetical benefit was
sought.

There was also the "Kinematic noise barrier," made of vertical
triangular slotted channels. It was utter bull, and the
measurements
claiming that it worked were laughable. That was the only barrier
construction that the Federal Highway Administration specifically
declared they would never fund.

Active control of an outdoor area is possible, and has been
demonstrated for jet aircraft runup noise. Active control requires
knowing the source with enough lead time (and/or predictability) to
generate the control sound. The problem with active control of
highway noise is that you have multiple sources, all moving and
uncorrelated with each other. Handling that is beyond anything that
can be done today.

Ken Plotkin

Hello Ken
thanks for the info it's nice to know someone else had tried these
idea's (it was just conjecture on my part).
I can also see the problems you mention, guess this is why there's
never been a solution (the patent would be worth a fortune).
Suppose the best think might be for him to plant some tree's at least
they will look better, and the leave rustling may mash the traffic
noise.
Although I think it was Audi or Mercedes that used the technology
inside the car to reduce road and traffic noise..

(Jonathan Epstein) wrote in message . com...
Hi,

I live about 100 yards from a major highway, and despite a noise
abatement wall have a significant noise level in my backyard. The
back of my house faces the highway, although there are two intervening
houses, a sidestreet, and the noise abatement wall. The noise is not
deafening, but is unpleasant.

I am thinking of constructing a screened-in porch adjacent to my house
in the backyard, but would be more inclined to do so if I could figure
out a way to reduce the noise level for those sitting inside the
porch.

I was thinking of directing two or three directional microphones on
the outside edge of the porch, towards the highway. I would then use
active noise cancellation to create a more pleasant environment for
those sitting on the porch.

My questions a
1. is this feasible? Will it work better with music playing (i.e., by
subtraction) or by attempting to add missing frequencies?
2. can this best be done using solely audio components, or best done
by computer?
3. if done by computer, which algorithms are appropriate? Psuedocode
would be welcome.

I have access to Matlab, at least for purposes of building a
prototype.

TIA,

Jonathan

Your best solution is probably lots and lots of mature trees. Hope
you're not in a hurry :-)
Seriously, though, consider putting in some trees, if not for your
own benefit then for future residents.

(Jonathan Epstein) wrote in message . com...
Hi,

I live about 100 yards from a major highway, and despite a noise
abatement wall have a significant noise level in my backyard. The
back of my house faces the highway, although there are two intervening
houses, a sidestreet, and the noise abatement wall. The noise is not
deafening, but is unpleasant.

I am thinking of constructing a screened-in porch adjacent to my house
in the backyard, but would be more inclined to do so if I could figure
out a way to reduce the noise level for those sitting inside the
porch.

I was thinking of directing two or three directional microphones on
the outside edge of the porch, towards the highway. I would then use
active noise cancellation to create a more pleasant environment for
those sitting on the porch.

My questions a
1. is this feasible? Will it work better with music playing (i.e., by
subtraction) or by attempting to add missing frequencies?
2. can this best be done using solely audio components, or best done
by computer?
3. if done by computer, which algorithms are appropriate? Psuedocode
would be welcome.

I have access to Matlab, at least for purposes of building a
prototype.

TIA,

Jonathan

Your best solution is probably lots and lots of mature trees. Hope
you're not in a hurry :-)
Seriously, though, consider putting in some trees, if not for your
own benefit then for future residents.

(Jonathan Epstein) wrote in message . com...
Hi,

I live about 100 yards from a major highway, and despite a noise
abatement wall have a significant noise level in my backyard. The
back of my house faces the highway, although there are two intervening
houses, a sidestreet, and the noise abatement wall. The noise is not
deafening, but is unpleasant.

I am thinking of constructing a screened-in porch adjacent to my house
in the backyard, but would be more inclined to do so if I could figure
out a way to reduce the noise level for those sitting inside the
porch.

I was thinking of directing two or three directional microphones on
the outside edge of the porch, towards the highway. I would then use
active noise cancellation to create a more pleasant environment for
those sitting on the porch.

My questions a
1. is this feasible? Will it work better with music playing (i.e., by
subtraction) or by attempting to add missing frequencies?
2. can this best be done using solely audio components, or best done
by computer?
3. if done by computer, which algorithms are appropriate? Psuedocode
would be welcome.

I have access to Matlab, at least for purposes of building a
prototype.

TIA,

Jonathan

Your best solution is probably lots and lots of mature trees. Hope
you're not in a hurry :-)
Seriously, though, consider putting in some trees, if not for your
own benefit then for future residents.

(Jonathan Epstein) wrote in message . com...
Hi,

I live about 100 yards from a major highway, and despite a noise
abatement wall have a significant noise level in my backyard. The
back of my house faces the highway, although there are two intervening
houses, a sidestreet, and the noise abatement wall. The noise is not
deafening, but is unpleasant.

I am thinking of constructing a screened-in porch adjacent to my house
in the backyard, but would be more inclined to do so if I could figure
out a way to reduce the noise level for those sitting inside the
porch.

I was thinking of directing two or three directional microphones on
the outside edge of the porch, towards the highway. I would then use
active noise cancellation to create a more pleasant environment for
those sitting on the porch.

My questions a
1. is this feasible? Will it work better with music playing (i.e., by
subtraction) or by attempting to add missing frequencies?
2. can this best be done using solely audio components, or best done
by computer?
3. if done by computer, which algorithms are appropriate? Psuedocode
would be welcome.

I have access to Matlab, at least for purposes of building a
prototype.

TIA,

Jonathan

Your best solution is probably lots and lots of mature trees. Hope
you're not in a hurry :-)
Seriously, though, consider putting in some trees, if not for your
own benefit then for future residents.