Noise dampening

J

James Varga

Guest
Okay - I have an idea here that I wanted to get soem feedback on and
hopefully some help with the circuit design.

I live by a really noisy road and wanted to try and build a noise
cancellation device. Kind of like what they use in some high-end cars. This
would be placed facing the window where the noise comes from and
essesntially read the sound - invert it - and play it back.

I'm guessing it would need to focus on the lower end of the spectrum as the
higher-end would get stopped by the window. (well most of it).

Any thoughts - examples - or ideas?
 
"James Varga" <james@jamesvarga.com> wrote in message
news:10m9tclmoik9kd9@corp.supernews.com...
Okay - I have an idea here that I wanted to get soem feedback on and
hopefully some help with the circuit design.

I live by a really noisy road and wanted to try and build a noise
cancellation device. Kind of like what they use in some high-end cars.
This
would be placed facing the window where the noise comes from and
essesntially read the sound - invert it - and play it back.

I'm guessing it would need to focus on the lower end of the spectrum as
the
higher-end would get stopped by the window. (well most of it).

Any thoughts - examples - or ideas?

At best, it would work at less than 200 Hz.
Click to expand...
 
"James Varga"
Okay - I have an idea here that I wanted to get soem feedback on and
hopefully some help with the circuit design.

I live by a really noisy road and wanted to try and build a noise
cancellation device. Kind of like what they use in some high-end cars.
This
would be placed facing the window where the noise comes from and
essesntially read the sound - invert it - and play it back.

I'm guessing it would need to focus on the lower end of the spectrum as
the
higher-end would get stopped by the window. (well most of it).

Any thoughts - examples - or ideas?
Click to expand...


** Forget it - the idea it has *zero* chance of working.

Try double glazing and sealing up all other possible paths of transmission
like via the floor or ceiling cavities.






............. Phil
 
** Forget it - the idea it has *zero* chance of working.
Click to expand...
Any idea of why? I've seen lots of references to these theories before - why
don't you think it would work?

Try double glazing and sealing up all other possible paths of
transmission
like via the floor or ceiling cavities.
Click to expand...
I already have double glazing and have sealed it up.

:)
 
"James Varga"

Okay - I have an idea here that I wanted to get soem feedback on and
hopefully some help with the circuit design.

I live by a really noisy road and wanted to try and build a noise
cancellation device. Kind of like what they use in some high-end cars.
This
would be placed facing the window where the noise comes from and
essesntially read the sound - invert it - and play it back.

I'm guessing it would need to focus on the lower end of the spectrum as
the
higher-end would get stopped by the window. (well most of it).

Any thoughts - examples - or ideas?
Click to expand...

** Forget it - the idea it has *zero* chance of working.

Any idea of why? I've seen lots of references to these theories before -
why
don't you think it would work?
Click to expand...

** None that do what you want.


Try double glazing and sealing up all other possible paths of
transmission like via the floor or ceiling cavities.

I already have double glazing and have sealed it up.

:)
Click to expand...

** Then you have no noise problem and are posting lies.



BTW DO NOT snip the subject out of site !!!





............. Phil
 
** Then you have no noise problem and are posting lies.
Click to expand...
Let me get this straight - so because I have double glazing and have done as
much as I can then I have no noise problem? Wow - what logic there. I would
invite you to come and listen for yourself and explain to my wife who has
been wearing ear plugs to bed for the past 2 years because she's a fairly
light sleeper - that its all in her head.

I was going to start with some sarcasim but I don't think its worth it.

BTW DO NOT snip the subject out of site !!!
Click to expand...
I probably wouldn't if it knew what you meant.
 
"James Varga"

** Replacing what this imbecile over snipped :

Okay - I have an idea here that I wanted to get soem feedback on and
hopefully some help with the circuit design.

I live by a really noisy road and wanted to try and build a noise
cancellation device. Kind of like what they use in some high-end cars.
This
would be placed facing the window where the noise comes from and
essesntially read the sound - invert it - and play it back.

I'm guessing it would need to focus on the lower end of the spectrum as
the
higher-end would get stopped by the window. (well most of it).

Any thoughts - examples - or ideas?


** Forget it - the idea it has *zero* chance of work

Try double glazing and sealing up all other possible paths of
transmission
like via the floor or ceiling cavities.

I already have double glazing and have sealed it up. :)


** Then you have no noise problem and are posting lies.


Let me get this straight - so because I have double glazing and have done
as
much as I can then I have no noise problem?
Click to expand...

** If you *actually* did as I suggested you will have no noise problem.

Obviously you have NOT - as your persistent snipping and bullshiting
reveals. Sealing against noise means AIRTIGHT sealing - depending on the
construction of your house this can be a MASSIVE job.


I was going to start with some sarcasim but I don't think its worth it.
Click to expand...

** Piss off you arrogant, snipping fool.




............... Phil
 
"Phil Allison" <philallison@tpg.com.au> wrote in message
news:41651303$1@dnews.tpgi.com.au...
"James Varga"

** Replacing what this imbecile over snipped :

Okay - I have an idea here that I wanted to get soem feedback on and
hopefully some help with the circuit design.

I live by a really noisy road and wanted to try and build a noise
cancellation device. Kind of like what they use in some high-end cars.
This
would be placed facing the window where the noise comes from and
essesntially read the sound - invert it - and play it back.

I'm guessing it would need to focus on the lower end of the spectrum as
the
higher-end would get stopped by the window. (well most of it).

Any thoughts - examples - or ideas?


** Forget it - the idea it has *zero* chance of work

Try double glazing and sealing up all other possible paths of
transmission
like via the floor or ceiling cavities.

I already have double glazing and have sealed it up. :)


** Then you have no noise problem and are posting lies.


Let me get this straight - so because I have double glazing and have
done
as
much as I can then I have no noise problem?


** If you *actually* did as I suggested you will have no noise problem.

Obviously you have NOT - as your persistent snipping and bullshiting
reveals. Sealing against noise means AIRTIGHT sealing - depending on
the
construction of your house this can be a MASSIVE job.


I was going to start with some sarcasim but I don't think its worth it.


** Piss off you arrogant, snipping fool.
Click to expand...
Wow - what a retort! - you are a witty character.

So - you think it would be appropriate to tare the hell out of house thats
been standing for 300 years just to seal it 'AIRTIGHT' ?

I was looking for more realistic solutions - not obsurd suggestions. But on
that note - why don't i just move .... build a new house even....
underground?.... in the artic??? that would work!

sheesh - very strong words for someone who didn't really offer a
constructive suggestion when all I was looking for was a bit of feedback and
thoughts on the subject. When I get a response like 'NO IT WILL NOT WORK'
(okay not that much yelling - but was close) I like to understand why before
I take someones word for it.

Take a pill big guy and lighten up a bit.
 
On Thu, 7 Oct 2004 10:25:35 +0100, "James Varga"
<james@jamesvarga.com> wrote:

** Then you have no noise problem and are posting lies.

Let me get this straight - so because I have double glazing and have done as
much as I can then I have no noise problem? Wow - what logic there. I would
invite you to come and listen for yourself and explain to my wife who has
been wearing ear plugs to bed for the past 2 years because she's a fairly
light sleeper - that its all in her head.

I was going to start with some sarcasim but I don't think its worth it.

BTW DO NOT snip the subject out of site !!!

I probably wouldn't if it knew what you meant.
Click to expand...
James, sorry you had to encounter Phil Allison - he is rude and
ignorant at his best.

As for your problem, it has been through the mill many, many times and
has never been resolved. You can expect to achieve a fair degree of
suppression by this method in a volume bounded by sides of probably no
bigger than one tenth of a wavelength. Beyond that, phase shifts will
have taken the situation beyond sensible control. It works best inside
a pair of headphones and has met with a slight degree of success in
up-market cars and light aircraft.

Mostly though if you want to stop noise, by far the most effective
method is to stop it getting in. If you double glaze, make the two
panes different thicknesses so they don't share a resonance. Put them
a reasonable distance apart to reduce coupling and make sure that even
the tiniest of air gaps are filled with some sort of sealer. You will
need to find some other way to ventilate the room.

d
Pearce Consulting
http://www.pearce.uk.com
 
Why don't you build one and try it. It sounds like an interesting project.

Naveed

"James Varga" <james@jamesvarga.com> wrote in message
news:10m9tclmoik9kd9@corp.supernews.com...
Okay - I have an idea here that I wanted to get soem feedback on and
hopefully some help with the circuit design.

I live by a really noisy road and wanted to try and build a noise
cancellation device. Kind of like what they use in some high-end cars.
This
would be placed facing the window where the noise comes from and
essesntially read the sound - invert it - and play it back.

I'm guessing it would need to focus on the lower end of the spectrum as
the
higher-end would get stopped by the window. (well most of it).

Any thoughts - examples - or ideas?
Click to expand...
 
"James Varga"
"Phil Allison"

** If you *actually* did as I suggested you will have no noise problem.

Obviously you have NOT - as your persistent snipping and bullshiting
reveals. Sealing against noise means AIRTIGHT sealing - depending on
the construction of your house this can be a MASSIVE job.

I was going to start with some sarcasim but I don't think its worth
it.

** Piss off you arrogant, snipping fool.


Wow - what a retort! - you are a witty character.
Click to expand...

** You are really a grade 1 ass.


So - you think it would be appropriate to tare the hell out of house thats
been standing for 300 years just to seal it 'AIRTIGHT' ?
Click to expand...

** Your problem - whatever you chose to keep secret.


I was looking for more realistic solutions - not obsurd suggestions.
Click to expand...

** More bullshit.

YOU came HERE with a totally absurd solution and wanted to shove it down
our throats.


But on
that note - why don't i just move .... build a new house even....
underground?.... in the artic??? that would work!
Click to expand...

** Take your pick.


sheesh - very strong words for someone who didn't really offer a
constructive suggestion when all I was looking for was a bit of feedback
and
thoughts on the subject.
Click to expand...

** Here is my first reply again - it could not be more constructive.

" ** Forget it - the idea it has *zero* chance of working.

Try double glazing and sealing up all other possible paths of
transmission
like via the floor or ceiling cavities. "


When I get a response like 'NO IT WILL NOT WORK'
(okay not that much yelling - but was close) I like to understand why
before
I take someones word for it.
Click to expand...

** Don't take my word - ask as many others as you like.

One has already confirmed my opinion.


Take a pill big guy and lighten up a bit.
Click to expand...

** What you need to do is a great deal of growing up.

But I fear that it is too late.




............ Phil
 
"Phil Allison" <philallison@tpg.com.au> wrote in message
news:41651303$1@dnews.tpgi.com.au...

Killfile for you Phill!

PLONK!
 
Rather than noise cancellation, you might try noise masking. You can
buy gizmos that sound like the seashore. Many people find that after
they get used to the seashore, they're not bothered by it's constant,
predictable sound nearly as much as the random outside sounds that it
masks.
Click to expand...

Good suggestion but I already tried that - unfortuantely. I think I'll have
a play around with it when I get a chance and see what happens but I thought
I would ask and see if anyone had any success with this.

Cheers!
 
Wont work?
tell that to Bose then . They have been doing that for 20 years in there
head sets.
An op amp with an inverting input is the basis of the circuit .With an
agc to regulate it . You have to have 2 signal sources to compare one
from the noise source and another from the area you want to protect.
Bruce

Phil Allison wrote:
"James Varga"

Okay - I have an idea here that I wanted to get soem feedback on and
hopefully some help with the circuit design.

I live by a really noisy road and wanted to try and build a noise
cancellation device. Kind of like what they use in some high-end cars.
This
would be placed facing the window where the noise comes from and
essesntially read the sound - invert it - and play it back.

I'm guessing it would need to focus on the lower end of the spectrum as
the
higher-end would get stopped by the window. (well most of it).

Any thoughts - examples - or ideas?




** Forget it - the idea it has *zero* chance of working.

Try double glazing and sealing up all other possible paths of transmission
like via the floor or ceiling cavities.






............ Phil
Click to expand...
 
James Varga wrote:

** Forget it - the idea it has *zero* chance of working.

Any idea of why? I've seen lots of references to these theories before - why
don't you think it would work?

Try double glazing and sealing up all other possible paths of
transmission
like via the floor or ceiling cavities.

I already have double glazing and have sealed it up.
Click to expand...
Triple glazing then ? Heavier glass ( that works well too ).

You really need to ascertain the major mode of sound transmission first though.

Graham
 
bruce wrote:

Wont work?
tell that to Bose then . They have been doing that for 20 years in there
head sets.
Click to expand...
That's somewhat different to doing the same in a *ROOM* !


Graham
 
"bruce" <
Wont work?
tell that to Bose then . They have been doing that for 20 years in there
head sets.
Click to expand...

* A headset houses only a TINY air volume to silence - even then it is far
from easy.

If you can create an *effective* room quietening system using mics and
speakers etc - the patent is worth billions.





............. Phil
 
"James Varga" <james@jamesvarga.com> wrote in message
news:10mbhc8a5vrlk45@corp.supernews.com...
Rather than noise cancellation, you might try noise masking. You can
buy gizmos that sound like the seashore. Many people find that after
they get used to the seashore, they're not bothered by it's constant,
predictable sound nearly as much as the random outside sounds that it
masks.

Good suggestion but I already tried that - unfortuantely. I think I'll
have
a play around with it when I get a chance and see what happens but I
thought
I would ask and see if anyone had any success with this.

Cheers!
Click to expand...
You need an adaptive filter based on the least-mean squares (LMS) method or
in fact filtered-x LMS. Are you trying to cancel the vibration of the house
in some way or just the noise that gets to your ear? For the latter, even if
it works there will be nodes and anti-nodes so that there will be areas
where the noise is worse!Normally the speakers are half a wavelength away so
you can do the sums.For example to cancel 200Hz the loudspeaker needs to be
lambda/2 metres away where lambda = 330/200 = 1.65m. So the loudspeaker
needs to be about 82cm away from the noise source.I doubt it will work
without an array of speakers - quite complicated and expensive.

As for doing it with a couple of op-amps - forget it! It would have to be
pretty periodic noise to work.Don't get me wrong, this idea is an old one
and is used in differential amplifiers for common mode noise rejection so
there are areas where it will work. You need to do a search for active noise
cancellation LMS. There are thousands of papers on the subject. Try comp.dsp
too.

Tom
 
To dampen something is to make that something moist.

The word you are looking for is damping.
Click to expand...
I'm sure everyone knew what I meant :)

Thanks everyone for your help - I'll see what I can come up with.
 
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