noise reduction material for window, noise from church bells

[dude-guy]

Hi,

I desperately need an opinion from someone with a good understanding
of materials or noise reduction in general.

I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?

Which transparent material reduces "church bell" sound waves the most?
I was told these guys make something that can reduce noise:
http://www.altuglas.com

Which frequencies do I need to reduce (freq. of sound from church
bell)?

How about optimal layer thickness of the transparent material?

Hope somebody is clever enough to help me find the best solution...

[Androcles]

Post by dude-guy
Hi,
I desperately need an opinion from someone with a good understanding
of materials or noise reduction in general.
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?
Which transparent material reduces "church bell" sound waves the most?
http://www.altuglas.com
Which frequencies do I need to reduce (freq. of sound from church
bell)?
How about optimal layer thickness of the transparent material?
Hope somebody is clever enough to help me find the best solution...

Best solution... dynamite the useless fuckin' church, bell and all.
Second best solution: sell your house to a campanologist then go
live next to an airport. My problem is noisy traffic, especially buses,
but double glazing is adequate unless I open a window.

[±]

you're an asshole

[Angelo Campanella]

Post by dude-guy
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?

Do NOT waste money on plastic products, as the mass (weight) is the
only sound reducing entity that will help, and glass is cheaper by the
pound.

Post by dude-guy
Which transparent material reduces "church bell" sound waves the most?
http://www.altuglas.com

Simply add thick glass "storm windows to the windows facing the bell
tower, and on windows on facades that are at right angles to same.

Post by dude-guy
Which frequencies do I need to reduce (freq. of sound from church
bell)?

The bell tones, likely above about 200 Hz, but that varies with size.

There is another aspect: Recently, pastors have become enamored with
electric bell chimes. Some believe they do the community a favor by
operating them loudly and frequently. Determine whether this is the case
for your location. If so, then register a complaint to the church
administration, that their chime operation is annoying to the residents.
Perhaps they could reduce it a a single daily Angelus at noon or 6pm.

Angelo Campanella

[dude-guy]

Post by dude-guy
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?

        Do NOT waste money on plastic products, as the mass (weight) is the
only sound reducing entity that will help, and glass is cheaper by the
pound.

That was also my first thought, until I got contact with a company who
says they successfully had used some PMMA plastic material from
http://www.altuglas.com/ - however I'm still in doubt about what to
do, as I would like a "neutral opinion" and this guy I talked to, he
was a seller...

Are you completely sure mass is the only thing to consider?

If that is the case, I would just go for a glass material with very
high density - and perhaps in all cases use 2 layers... If I have to
use more layers, it'll become very ugly...

Does it matter whether it's high or low frequent noise?

My immediate idea is that high frequency noise perhaps can be filtered
with plastics (PMMA), but perhaps low frequency noise cannot and needs
mass...

Post by dude-guy
Which transparent material reduces "church bell" sound waves the most?
http://www.altuglas.com

        Simply add thick glass "storm windows to the windows facing the bell
tower, and on windows on facades that are at right angles to same.

I agree, it sounds like a solution. Does that kind of glass you're
talking about has a special name other than "storm glass"?

Post by dude-guy
Which frequencies do I need to reduce (freq. of sound from church
bell)?

        The bell tones, likely above about 200 Hz, but that varies with size.
        There is another aspect: Recently, pastors have become enamored with
electric bell chimes. Some believe they do the community a favor by
operating them loudly and frequently. Determine whether this is the case
for your location. If so, then register a complaint to the church
administration, that their chime operation is annoying to the residents.
Perhaps they could reduce it a a single daily Angelus at noon or 6pm.

This one is definately not electrical. I know that for sure after
having talked to them and complained... It's operated manually and I
can see the bell vibrate, while the noise is bugging me for every bell
chime...

[N:dlzc D:aol T:com (dlzc)]

Dear dude-guy:

"dude-guy" <***@gmail.com> wrote in message news:f94ae6f0-00ba-4dba-ab45-***@l42g2000hsc.googlegroups.com...
On 25 Sep., 19:18, Angelo Campanella <***@att.net>
wrote:
...

Post by dude-guy

Post by Angelo Campanella

Should this extra layer be real "window glass" or
polymeric/plastic "PMMA"?

Do NOT waste money on plastic products, as the
mass (weight) is the only sound reducing entity
that will help, and glass is cheaper by the pound.

That was also my first thought, until I got contact
with a company who says they successfully had
used some PMMA plastic material from

http://www.altuglas.com/

Post by dude-guy
- however I'm still in doubt about what to do, as I
would like a "neutral opinion" and this guy I talked
to, he was a seller...
Are you completely sure mass is the only thing
to consider?

Only thing, no. The material's ability to dampen vibration (good
for polymer, poor for glass), and mechanical isolation. Triple
paned glass is like a wall, for both sound and heat transfer
(well...)

Post by dude-guy
Does it matter whether it's high or low frequent
noise?

The spacing between panes will decide whether it dampens /
isolates or resonates / amplifies the noise.

David A. Smith

[dude-guy]

Post by dude-guy
Are you completely sure mass is the only thing
to consider?

Only thing, no.  The material's ability to dampen vibration (good
for polymer, poor for glass), and mechanical isolation.  Triple

Yes, this is also what I thought...

Polymer = good at damping vibrations...
Glass = has higher density...

What should I choose? What is the optimal / the best, when there's
already 1 layer of glass (actually 2 thin layers, it's a thermo-
isolating window for cold winters)...

paned glass is like a wall, for both sound and heat transfer
(well...)

Post by dude-guy
Does it matter whether it's high or low frequent
noise?

The spacing between panes will decide whether it dampens /
isolates or resonates / amplifies the noise.

How to find the best spacing for absorbing noise from church bells?

What would you recommend?

[dlzc]

Post by dude-guy

Post by dude-guy
Are you completely sure mass is the only thing
to consider?

Only thing, no.  The material's ability to dampen
vibration (good for polymer, poor for glass), and
mechanical isolation.  Triple

Yes, this is also what I thought...
Polymer = good at damping vibrations...
Glass = has higher density...
What should I choose?

Both, if sandwiched.

Post by dude-guy
What is the optimal / the best, when there's
already 1 layer of glass (actually 2 thin
layers, it's a thermo-isolating window for cold
winters)...

paned glass is like a wall, for both sound
and heat transfer
(well...)

Post by dude-guy
Does it matter whether it's high or low frequent
noise?

The spacing between panes will decide whether
it dampens / isolates or resonates / amplifies
the noise.

How to find the best spacing for absorbing noise
from church bells?
What would you recommend?

The mathematics on spacing will be similar to the length of an organ
pipe, only closed at both ends. 1 to 2 inches in length (separation)
will not respond well to the first few harmonics of the bell's tone.

Almost anything will be better than nothing.

David A. Smith

[dude-guy]

Post by dlzc

Post by dude-guy

Only thing, no.  The material's ability to dampen
vibration (good for polymer, poor for glass), and
mechanical isolation.  Triple

Yes, this is also what I thought...
Polymer = good at damping vibrations...
Glass = has higher density...
What should I choose?

Both, if sandwiched.

OMG... Now we're back again to the mass discussion. Is mass (real
glass, not polymers) the most important thing or is it the ability to
absorb noise (polymers, lower density)?

Some people say glass is the only thing to consider (double layer) and
now you say polymer (since there's already glass)... Is it strange I'm
confused?

Post by dlzc

Post by dude-guy
What is the optimal / the best, when there's
already 1 layer of glass (actually 2 thin
layers, it's a thermo-isolating window for cold
winters)...

paned glass is like a wall, for both sound
and heat transfer
(well...)

Post by dude-guy
Does it matter whether it's high or low frequent
noise?

The spacing between panes will decide whether
it dampens / isolates or resonates / amplifies
the noise.

How to find the best spacing for absorbing noise
from church bells?
What would you recommend?

The mathematics on spacing will be similar to the length of an organ
pipe, only closed at both ends.  1 to 2 inches in length (separation)
will not respond well to the first few harmonics of the bell's tone.

I've probably seen something like that before, but how do you
calculate the harmonics?

Since this is posted to materials science and acoustics science
group(s), I hope somebody knows how to calculate it and can show the
equations for the rest of us?

Post by dlzc
Almost anything will be better than nothing.

Yes, agreed and something must (and will) happen... I just want "the
best solution" and get to a good understanding of the important
variables to choose the solution from (before spending my money on
something that could later turn out to be more or less useless)...

[dlzc]

...

Post by dude-guy

Post by dlzc

Post by dude-guy
Yes, this is also what I thought...
Polymer = good at damping vibrations...
Glass = has higher density...
What should I choose?

Both, if sandwiched.

OMG... Now we're back again to the mass
discussion. Is mass (real glass, not
polymers) the most important thing or is it
the ability to absorb noise (polymers, lower
density)?

What makes you think there is only one "most important thing"? You or
others have said they can hear voices outside their mulitply-glazed
windows near resonant frequencies. Dampening, such as provided by a
polymer substrate, can reduce even that noise.

Post by dude-guy
Some people say glass is the only thing to
consider (double layer) and now you say
polymer (since there's already glass)... Is it
strange I'm confused?

Yes. Read the word "sandwich" above. Glass for mass, polymer for
dampening.

As to mathematics:
http://hyperphysics.phy-astr.gsu.edu/hbase/class/phscilab/restube2.html
... and just adjust the lengths arrived at by 2/3, since this is based
on one end open. But until you know the bell's tone / frequency
range...

...

Post by dude-guy

Post by dlzc
Almost anything will be better than nothing.

Yes, agreed and something must (and will)
happen... I just want "the best solution" and
get to a good understanding of the important
variables to choose the solution from (before
spending my money on something that
could later turn out to be more or less
useless)...

Anything you do, even "non-optimal" but still recommended on this
group, will be a noticeable improvement.

David A. Smith

[Angelo Campanella]

Post by dude-guy

Post by Angelo Campanella
Do NOT waste money on plastic products, as the mass (weight) is the
only sound reducing entity that will help, and glass is cheaper by the
pound.

That was also my first thought, until I got contact with a company who
says they successfully had used some PMMA plastic material from
http://www.altuglas.com/ - however I'm still in doubt about what to
do, as I would like a "neutral opinion" and this guy I talked to, he
was a seller...

Plastic will be more expensive than glass except for the thinnest of
plastic sheets, little more than 1/16" thick, which is very light.

Post by dude-guy
Are you completely sure mass is the only thing to consider?

for high noise attenuation, it is the best.

Post by dude-guy
If that is the case, I would just go for a glass material with very
high density - and perhaps in all cases use 2 layers... If I have to
use more layers, it'll become very ugly...

I would not bother with "high density glass" since it may be pricey,
and may be more apt to crack. I recommend conventional window glass
since it is tempered for window usage.

Ordinary window pane glass is called "single strength" (SSG). it's
barely over 1/6" thick, perhaps 3/32" thick. Heavier window glass is
called "double strength glass" (DSG). This, I think, is what is used for
most larger storm windows. It's about 1/8" thick, I think. The next step
up is 3/16" plate glass, then 1/4" plate glass, etc.

Post by dude-guy
Does it matter whether it's high or low frequent noise?

To some extent it does. first of all, the heaviest glass is required to
stop low frequency noise (drums, boom boxes and car stereo thumping).
Less mass is needed for mid frequencies, but it may still be necessary
when you want a high degree of noise reduction. An anomaly occurs at the
"coincidence frequency" for a stiff plate such as glass, where it will
transmit sound in a narrow band around 2,000 to 2,000 Hz. In this regard
the plastic sheet, as light as it is, has a coincidence frequency at or
above 10,000 Hz, which is of no consequence. A good compromise is one
pane of thick plastic combined with a glass pane with a 2" gap inside.
This makes for a thicker package.

Post by dude-guy
My immediate idea is that high frequency noise perhaps can be filtered
with plastics (PMMA)

OK.. combo of coincidence frequency being out of the picture, but it
only works well for high frequency sound.

, but perhaps low frequency noise cannot and needs

Post by dude-guy
mass...

Yes.

Post by dude-guy
I agree, it sounds like a solution. Does that kind of glass you're
talking about has a special name other than "storm glass"?

The SSG and DSG and thicker panes were described. There is no such
thing as storm glass. To be sure, one could tag that name onto plastic
since it is more robust in high winds. (But plastic is troublesome in
very cold air since it shrinks much more than does glass, so the edge
clamping strip and frame have to be wider.)

Post by dude-guy

Post by Angelo Campanella
The bell tones, likely above about 200 Hz, but that varies with size.

You would have to try a storm window, either store-bought or built by
you. It should be located as far as possible from the existing window
pane.; at least 2" and preferably 4" or more if possible. In the "old
days" (when I was growing up), the first storm windows I saw were framed
to the molding around the window on the outside facade. These make the
best noise attenuator. since the air gap is then many inches, and the
glass used ware DSG for surviving the winter blasts, etc..

Post by dude-guy
This one is definately not electrical. I know that for sure after
having talked to them and complained... It's operated manually and I
can see the bell vibrate, while the noise is bugging me for every bell
chime...

It's intended to be heard for great distances...


Angelo Campanella

[Angelo]

Difficult to achieve, but double glass filled with water, will isolate the
sound. But then you still have other entrances of noise -walls, slots,
cokeer-hood, reflections from buildings near you...

Post by dude-guy
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?

Do NOT waste money on plastic products, as the mass (weight) is the only
sound reducing entity that will help, and glass is cheaper by the pound.

Post by dude-guy
Which transparent material reduces "church bell" sound waves the most?
http://www.altuglas.com

Simply add thick glass "storm windows to the windows facing the bell
tower, and on windows on facades that are at right angles to same.

Post by dude-guy
Which frequencies do I need to reduce (freq. of sound from church
bell)?

The bell tones, likely above about 200 Hz, but that varies with size.
There is another aspect: Recently, pastors have become enamored with
electric bell chimes. Some believe they do the community a favor by
operating them loudly and frequently. Determine whether this is the case
for your location. If so, then register a complaint to the church
administration, that their chime operation is annoying to the residents.
Perhaps they could reduce it a a single daily Angelus at noon or 6pm.
Angelo Campanella

[dlzc]

Dear dude-guy:

On Sep 25, 8:31 am, dude-guy <***@gmail.com> wrote:
...

Post by dude-guy
Which frequencies do I need to reduce (freq. of sound
from church bell)?

2000 Hz and down, usually.

Post by dude-guy
How about optimal layer thickness of the transparent
material?

Give up. You need a second wall and ceiling, with mechanical
isolation between the two.

Post by dude-guy
Hope somebody is clever enough to help me find the
best solution...

Most economical solutions:
1) move.
2) attend the church.
3) noise cancelling headphones.
4) join the Hells Angels, and make sure to circle the church during
services.
5) remove the striker.
6) coat the striker with contact explosive.
7) fire / throw massive objects at the bell when the minister /
preacher / priest is conducting services.

Some of those might involve some jail time...

David A. Smith

[Androcles]

"dlzc" <***@cox.net> wrote in message news:2fc1dd51-2930-4676-961f-***@k37g2000hsf.googlegroups.com...
Dear dude-guy:

On Sep 25, 8:31 am, dude-guy <***@gmail.com> wrote:
...

Post by dude-guy
Which frequencies do I need to reduce (freq. of sound
from church bell)?

2000 Hz and down, usually.

Post by dude-guy
How about optimal layer thickness of the transparent
material?

Give up. You need a second wall and ceiling, with mechanical
isolation between the two.

Post by dude-guy
Hope somebody is clever enough to help me find the
best solution...

Most economical solutions:
1) move.
2) attend the church.
3) noise cancelling headphones.
4) join the Hells Angels, and make sure to circle the church during
services.
5) remove the striker.
6) coat the striker with contact explosive.
7) fire / throw massive objects at the bell when the minister /
preacher / priest is conducting services.

Some of those might involve some jail time...

David A. Smith
==========================================
Ringing hand bells in church during services or overturning
the money changer's passed plate could be amusing.

[Clyde Slick]

Post by dlzc
...

Post by dude-guy
Which frequencies do I need to reduce (freq. of sound
from church bell)?

2000 Hz and down, usually.

Post by dude-guy
How about optimal layer thickness of the transparent
material?

Give up.  You need a second wall and ceiling, with mechanical
isolation between the two.

Post by dude-guy
Hope somebody is clever enough to help me find the
best solution...

1) move.
2) attend the church.
3) noise cancelling headphones.
4) join the Hells Angels, and make sure to circle the church during
services.
5) remove the striker.
6) coat the striker with contact explosive.
7) fire / throw massive objects at the bell when the minister /
preacher / priest is conducting services.
Some of those might involve some jail time...

Prisons can be quite noisy, too, from what
I have seen on reality tv shows.
Sorry, but I have no personal experience.
Besides, this poor guy just might
have the misfortune to be housed
in a prison right next to a church, the worst of both worlds.

[unknown]

On Thu, 25 Sep 2008 08:31:08 -0700 (PDT), dude-guy

Post by dude-guy
Hi,
I desperately need an opinion from someone with a good understanding
of materials or noise reduction in general.
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?
Which transparent material reduces "church bell" sound waves the most?
http://www.altuglas.com
Which frequencies do I need to reduce (freq. of sound from church
bell)?
How about optimal layer thickness of the transparent material?
Hope somebody is clever enough to help me find the best solution...

Convert to Islam and do muezzin exercises calling for prayer,
when they ring the bells, that is.

w.

[Androcles]

Post by unknown
On Thu, 25 Sep 2008 08:31:08 -0700 (PDT), dude-guy

Post by dude-guy
Hi,
I desperately need an opinion from someone with a good understanding
of materials or noise reduction in general.
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?
Which transparent material reduces "church bell" sound waves the most?
http://www.altuglas.com
Which frequencies do I need to reduce (freq. of sound from church
bell)?
How about optimal layer thickness of the transparent material?
Hope somebody is clever enough to help me find the best solution...

Convert to Islam and do muezzin exercises calling for prayer,
when they ring the bells, that is.
w.

Wabbie, that is the most intelligent and humorous reply I've seen.
How come you are such a dickhead when it comes to physics?

[±]

In my business, we built to rooms to house punch presses which are very
loud when they are running. The rooms are standard 2x4 construction.
They have large 4 x 8 windows in them on two walls. The windows are
created by two sheets of 1/8 thick polycarbonate separated by 3" of air
in between them. Everyone is surprised at how quiet the presses are
even close proximity to others working. Subjectively, these double
windows seem to dampen the noise at least as well as the rest of the
enclosure. For what it's worth.

Post by dude-guy
Hi,
I desperately need an opinion from someone with a good understanding
of materials or noise reduction in general.
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?
Which transparent material reduces "church bell" sound waves the most?
http://www.altuglas.com
Which frequencies do I need to reduce (freq. of sound from church
bell)?
How about optimal layer thickness of the transparent material?
Hope somebody is clever enough to help me find the best solution...

[Tony]

Post by dude-guy
Which transparent material reduces "church bell" sound waves the most?

If you are using a single sheet, the answer is acoustic laminated glass, the
thicker the better. However I assume you will be adding a layer to your
existing windows. In this case acoustic laminated glass might not be worth
its extra cost. You should use ordinary glass, the thicker the better - I
would suggest 10 mm or 3/8 inch. In ordinary buildings it is not usually
worth going above this as sound will also come through the rest of the
structure, air leaks, doors etc. (Don't expect silence!) The gap between
the new pane and the existing should be as much as you can manage up to 150
mm max. Don't go for plastic if you want much useful effect, you need
weight.

It will also help a lot if the space around the edge between the two panes
is lined with sound absorbent material, for example sound absorbing plastic
foam. Also if you do this you will still get a bit of noise reduction even
if you have openings for air, provided that the openings are not opposite
each other.

[OG]

Post by dude-guy
Hi,
I desperately need an opinion from someone with a good understanding
of materials or noise reduction in general.
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?
Which transparent material reduces "church bell" sound waves the most?
http://www.altuglas.com
Which frequencies do I need to reduce (freq. of sound from church
bell)?
How about optimal layer thickness of the transparent material?
Hope somebody is clever enough to help me find the best solution...

Have you found this web page ?
http://irc.nrc-cnrc.gc.ca/pubs/cbd/cbd240_e.html

Basically, you want to add a secondary glazing layer with a wide gap between
the existing glass and the new glass. If you have different thicknesses of
glass for each layer you can increase the sound deadening effect. The amount
of noise insulation will depend on your window frame material as well. Wood
is good, thin metal is worse, it is possible to add sound deadening fillings
to hollow frames.

Using laminated glass can provide increased noise insulation compared to
plain glass.

[dude-guy]

Post by dude-guy
Hi,
I desperately need an opinion from someone with a good understanding
of materials or noise reduction in general.
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?
Which transparent material reduces "church bell" sound waves the most?
http://www.altuglas.com
Which frequencies do I need to reduce (freq. of sound from church
bell)?
How about optimal layer thickness of the transparent material?
Hope somebody is clever enough to help me find the best solution...

Have you found this web page ?http://irc.nrc-cnrc.gc.ca/pubs/cbd/cbd240_e.html

I didn't find it myself so thank you very much. Very good article...

[GregS]

Post by dude-guy
Hi,
I desperately need an opinion from someone with a good understanding
of materials or noise reduction in general.
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?
Which transparent material reduces "church bell" sound waves the most?
http://www.altuglas.com
Which frequencies do I need to reduce (freq. of sound from church
bell)?
How about optimal layer thickness of the transparent material?
Hope somebody is clever enough to help me find the best solution...

Do you now have a energy double panned window. Thats the first step.


greg

[OG]

In article

Post by dude-guy
Hope somebody is clever enough to help me find the best solution...

Do you now have a energy double panned window. Thats the first step.

Double Glazing for sound reduction requires a significantly wider gap than
DG for heat loss reduction.

[OG]

Post by OG

In article

Post by dude-guy
Hope somebody is clever enough to help me find the best solution...

Do you now have a energy double panned window. Thats the first step.

Double Glazing for sound reduction requires a significantly wider gap than
DG for heat loss reduction.

Forgot to add
Mind you I'm not an acoustic engineer so I'm happy to be corrected!

[Asbjørn]

Post by OG

Post by OG

In article

Post by dude-guy
Hope somebody is clever enough to help me find the best solution...

Do you now have a energy double panned window. Thats the first step.

Double Glazing for sound reduction requires a significantly wider gap
than DG for heat loss reduction.

Forgot to add
Mind you I'm not an acoustic engineer so I'm happy to be corrected!

The simple main rule for sound insulation is
The inner and outer layer should be as heavy as possible in kg/m2 (lb/ft2),
and the gap between should be as large as possible.
With windows, that means 8 - 12 mm (1/4 - 1/2") glass on both sides of at
least 50 -150 mm (2 - 6") gap.
Any glass between the inner and outer glas (e.g. the inner glass of a thin
DG) will not contribute.
Laminated glass will usually not be worth the extra cost.
Do not forget to seal well around the glass and frames, and close the vents.
May be you also should improve the walls (and ceiling?), with some layers of
gypsum board on board walls, or with at least 50 mm insulation mats behind
on brick or concrete..
But no matter what you do, you will still hear the bells.

- Asbjørn

[Tony]

"Asbj�rn" <***@frisurf.no> wrote in message news:gbje64$9nj$***@news.get.no...
(sensible suggestions, but only in alt.sci.physics.acoustics)

I've set this back to all the original groups in case the OP isn't reading
alt.sci.physics.acoustics.
I see that a reasonably consistent consensus of technical opinion is now
appearing. The system does work sometimes!

[OG]

Post by Tony
(sensible suggestions, but only in alt.sci.physics.acoustics)
I've set this back to all the original groups in case the OP isn't reading
alt.sci.physics.acoustics.
I see that a reasonably consistent consensus of technical opinion is now
appearing. The system does work sometimes!
--
Tony W

So far as I can tell, the only posting that is isn't in most threads is
Asbjørn's . Suggest the OP goes to a.s.p.a for the missing post.

[Asbjørn]

Post by OG

Post by Tony
(sensible suggestions, but only in alt.sci.physics.acoustics)
I've set this back to all the original groups in case the OP isn't
reading alt.sci.physics.acoustics.
I see that a reasonably consistent consensus of technical opinion is now
appearing. The system does work sometimes!
--
Tony W

So far as I can tell, the only posting that is isn't in most threads is
Asbjørn's . Suggest the OP goes to a.s.p.a for the missing post.

Sorry, I got an error when posting to all the original groups, so I just
deleted the others.
Feel free to forward if you think it was of use.
- Asbjørn

[Asbjørn]

Still sorry for my bad news connections.
Just trying to give some simple explanations,

Post by dude-guy

Post by Asbjørn
The simple main rule for sound insulation is
The inner and outer layer should be as heavy as possible in kg/m2 (lb/ft2),
and the gap between should be as large as possible.

So plastic/polymers doesn't absorb noise more?

Mass is the most important factor. Glass has higher density.
Laminating glass with plastic gives higher loss factor (damping) which
helps at the resonnance frequencies, and is fine when total thickness is
restricted, but adding mass or gap gives more and is cheaper.

Post by dude-guy

Post by Asbjørn
With windows, that means 8 - 12 mm (5/16 - 1/2") glass on both sides of
at
least 50 -150 mm (2 - 6") gap.
Any glass between the inner and outer glas (e.g. the inner glass of a thin
DG) will not contribute.

Why not???

Dividing the cavity result in more and higher resonnance frequencies,
usually in the critical frequency range.
Increasing the cavity lowers the "double wall" resonnance frequency so
the insulation gets to start rising at a lower frequency.(There is

Post by dude-guy
How about plastics/polymers between?
Please explain why extra mass in the middle doesn't help?

Post by Asbjørn
Laminated glass will usually not be worth the extra cost.

Agree.

Post by Asbjørn
Do not forget to seal well around the glass and frames, and close the vents.
May be you also should improve the walls (and ceiling?), with some layers of
gypsum board on board walls, or with at least 50 mm insulation mats behind
on brick or concrete..
But no matter what you do, you will still hear the bells.

Agree - noise level should just be lowered...>

[dude-guy]

Post by Asbjørn
Still sorry for my bad news connections.
Just trying to give some simple explanations,

Post by dude-guy

Post by Asbjørn
The simple main rule for sound insulation is
The inner and outer layer should be as heavy as possible in kg/m2 (lb/ft2),
and the gap between should be as large as possible.

So plastic/polymers doesn't absorb noise more?

    Mass is the most important factor. Glass has higher density.
    Laminating glass with plastic gives higher loss factor (damping) which
helps at the resonnance frequencies, and is fine when total thickness is
restricted, but adding mass or gap gives more and is cheaper.

Ok, you sound like somebody who really knows something about this.

I just didn't understand yet (could you please explain this): Why is
that adding a large gap means much? What happens?

Do you have some equation where you can show me that large distance =
great noise reduction?

I assume this has something to do with standing waves / pipe organ
equations or something, but can someone please explain what happens to
the sound waves, when increasing the distance and why it damps so much
better?

Post by Asbjørn

Post by dude-guy

Post by Asbjørn
With windows, that means 8 - 12 mm (5/16 - 1/2") glass on both sides of
at
least 50 -150 mm (2 - 6") gap.
Any glass between the inner and outer glas (e.g. the inner glass of a thin
DG) will not contribute.

Why not???

    Dividing the cavity result in more and higher resonnance frequencies,
usually in the critical frequency range.

On the other hand, there's more mass.... And you previously said that
was also (very) important?!?

Please show an equation, so I can understand it. I have a background
in mech. engineering, so I should be able to read up on it, if I get
the basic idea...

[GregS]

Post by dude-guy

Post by Asbjørn
Still sorry for my bad news connections.
Just trying to give some simple explanations,

Post by dude-guy

Post by Asbjørn
The simple main rule for sound insulation is
The inner and outer layer should be as heavy as possible in kg/m2 (lb/ft2),
and the gap between should be as large as possible.

So plastic/polymers doesn't absorb noise more?

=A0 =A0 Mass is the most important factor. Glass has higher density.
=A0 =A0 Laminating glass with plastic gives higher loss factor (damping) =

which

Post by Asbjørn
helps at the resonnance frequencies, and is fine when total thickness is
restricted, but adding mass or gap gives more and is cheaper.

Ok, you sound like somebody who really knows something about this.
I just didn't understand yet (could you please explain this): Why is
that adding a large gap means much? What happens?
Do you have some equation where you can show me that large distance =3D
great noise reduction?
I assume this has something to do with standing waves / pipe organ
equations or something, but can someone please explain what happens to
the sound waves, when increasing the distance and why it damps so much
better?

Suppose you take two pieces of glass and separate them by enough so they don't touch.
Don't you think there would be a greater air pressure forced into the other than with a foot
separation.

Post by dude-guy

Post by Asbjørn

Post by dude-guy

Post by Asbjørn
With windows, that means 8 - 12 mm (5/16 - 1/2") glass on both sides o=

f

Post by Asbjørn

Post by dude-guy

Post by Asbjørn
at
least 50 -150 mm (2 - 6") gap.
Any glass between the inner and outer glas (e.g. the inner glass of a thin
DG) will not contribute.

Why not???

=A0 =A0 Dividing the cavity result in more and higher resonnance frequenc=

ies,

Post by Asbjørn
usually in the critical frequency range.

On the other hand, there's more mass.... And you previously said that
was also (very) important?!?
Please show an equation, so I can understand it. I have a background
in mech. engineering, so I should be able to read up on it, if I get
the basic idea...

[dude-guy]

Post by GregS

Post by dude-guy
Ok, you sound like somebody who really knows something about this.
I just didn't understand yet (could you please explain this): Why is
that adding a large gap means much? What happens?
Do you have some equation where you can show me that large distance =3D
great noise reduction?
I assume this has something to do with standing waves / pipe organ
equations or something, but can someone please explain what happens to
the sound waves, when increasing the distance and why it damps so much
better?

Suppose you take two pieces of glass and separate them by enough so they don't touch.
Don't you think there would be a greater air pressure forced into the other than with a foot
separation.

No, frankly I don't. I think the pressure of the air would be the same
as that for the atmosphere no matter the distance (unless you force
it, i.e. blow it in or or create vacuum or do something else).

[Angelo Campanella]

Post by dude-guy

Post by GregS

Post by dude-guy
Ok, you sound like somebody who really knows something about this.
I just didn't understand yet (could you please explain this): Why is
that adding a large gap means much? What happens?
Do you have some equation where you can show me that large distance =3D
great noise reduction?
I assume this has something to do with standing waves / pipe organ
equations or something, but can someone please explain what happens to
the sound waves, when increasing the distance and why it damps so much
better?

Suppose you take two pieces of glass and separate them by enough so they don't touch.
Don't you think there would be a greater air pressure forced into the other than with a foot
separation.

No, frankly I don't. I think the pressure of the air would be the same
as that for the atmosphere no matter the distance (unless you force
it, i.e. blow it in or or create vacuum or do something else).

The air gap is what makes the noise isolation better at audio frequencies.

This discussion is degenerating into babble.

Above the mass-spring frequency, the mass of the two glass panenes act
as a 2-pole low pass filter. he rollover frequency is

F = 170/Sqrt(MD)

where m is the effective mass of the pair of free masses,

M= M1*M2/(M1+M2)

and D is the sepaation in inckes.

Flor glass weighing one pound per square foot,

M=1*1/(1+1)=0.5

For D= 12"

F=170/Sqrt(0.5*12) = 69 Hz.

Above 69 Hz, the sound attenuation (insertion loss) increases rapidly
with frequency.

There are various theoretical "estimates" of such attenuation, but the
only way to really determine it to build one and try it. My experience
for such a window (I have specified and tested one such for an audio
control room window at Ball State University Telecommnications learning
center in late 1980's. I tested it as about FSTC 54.

Angelo Campanella

[Don Pearce]

Post by Angelo Campanella

Post by dude-guy

In article

Post by dude-guy
Ok, you sound like somebody who really knows something about this.
I just didn't understand yet (could you please explain this): Why is
that adding a large gap means much? What happens?
Do you have some equation where you can show me that large distance =3D
great noise reduction?
I assume this has something to do with standing waves / pipe organ
equations or something, but can someone please explain what happens to
the sound waves, when increasing the distance and why it damps so much
better?

Suppose you take two pieces of glass and separate them by enough so they don't touch.
Don't you think there would be a greater air pressure forced into the
other than with a foot
separation.

No, frankly I don't. I think the pressure of the air would be the same
as that for the atmosphere no matter the distance (unless you force
it, i.e. blow it in or or create vacuum or do something else).

The air gap is what makes the noise isolation better at audio frequencies.
This discussion is degenerating into babble.
Above the mass-spring frequency, the mass of the two glass panenes
act as a 2-pole low pass filter. he rollover frequency is
F = 170/Sqrt(MD)
where m is the effective mass of the pair of free masses,
M= M1*M2/(M1+M2)
and D is the sepaation in inckes.
Flor glass weighing one pound per square foot,
M=1*1/(1+1)=0.5
For D= 12"
F=170/Sqrt(0.5*12) = 69 Hz.
Above 69 Hz, the sound attenuation (insertion loss) increases rapidly
with frequency.
There are various theoretical "estimates" of such attenuation, but
the only way to really determine it to build one and try it. My
experience for such a window (I have specified and tested one such for
an audio control room window at Ball State University Telecommnications
learning center in late 1980's. I tested it as about FSTC 54.
Angelo Campanella

Angelo, have you ever tried this with the glass panes forced into a
slight curve by the frame? Stiffness against an incident acoustic wave
is increased considerably.

d

[Angelo Campanella]

Post by Don Pearce

Post by Angelo Campanella
Above 69 Hz, the sound attenuation (insertion loss) increases rapidly
with frequency.
There are various theoretical "estimates" of such attenuation, but
the only way to really determine it to build one and try it. My
experience for such a window (I have specified and tested one such for
an audio control room window at Ball State University
Telecommnications learning center in late 1980's. I tested it as about
FSTC 54.

Angelo, have you ever tried this with the glass panes forced into a
slight curve by the frame? Stiffness against an incident acoustic wave
is increased considerably.

That is an interesting hypothesis. That stiffness will interact with
two phenomena:

1- The higher bending stiffness in one direction will raise the
coincidence frequency above the 2500 Hz resonance "achilles heel" of
window glass. The other direction will still demonstrate coincidence
transmission around 2500 Hz, I think.

2- The panel resonance of 69 Hz may or not be affected because that
resonance is by the panel alone. It is more significant that stiffness
offered by the frame will interact with a flat pane. More clamping
stiffness will *raise* the resonance frequency above 69 Hz (as will also
the curved panel surface), placing it again back in the middle audio
range, which we do NOT want to do. It is best that the glass pane be
held by limp (soft rubber) supports at its edge and be flat, I think.
Again, this is all speculation. One has to build it and try it.

Similarly, I do not use tilted glass panes for audio control windows
despite their "sexy" appearance for two reasons.

1- The effectiveness in noise isolation strongly depends on the minimum
spacing rather than the maximum spacing in that wedged space. Hence, if
one wants maximum sound attenuation, one spaces the glass surfaces as
far apart as possible.

[The absolute best sound attenuation will occur for an interior window
when you simply cut a hole of any size or shape clear through that wall.
Leave the stud cavity OPEN to the window gap. Set fiberglass in the stud
gap within the wall. Spray paint it black if you don't like to see pink
or yellow there. (The one and only application of Sonex I have ever
recommended has been as an ersatz black cover for this gap. It is in the
studio windows at Ball State Communications Complex.) DON'T cover that
gap with a flat plate of any sort, as this will trap sound in the window
gap and deteriorate the sound attenuation. (Ugly but good follows:) Cut
two sheets of plate glass oversize to cover the window hole plus a 2" to
4" margin all around. Either RTV the glass to the wall all around, or
build a picture frame of wood to secure it if you don't like that much
ugly. Caulk the entire glass edge perimeter before laying that frame.
Treat the other side of the wall exactly the same way. This window will
have HIGHER sound attenuation than the surrounding wall.]

2- Titled panes always produce new reflections of ceiling and perimeter
lights and lit objects than is normally experienced. This can be very
annoying for everyday use.

Cheers,

Angelo Campanella

[Tony]

Post by Angelo Campanella
1- The effectiveness in noise isolation strongly depends on the minimum
spacing rather than the maximum spacing in that wedged space. Hence, if
one wants maximum sound attenuation, one spaces the glass surfaces as
far apart as possible.

What's the theoretical basis for that Angelo? I have always assumed it was
the average spacing that mattered.

I agree that tilting panes is not effective for improving isolation and is
often counter-productive for reducing light reflections, but it is sometimes
necessary in a low RT room for stopping a flutter echo. Of course, in
practice increasing the average spacing and increasing the minimum spacing
will often come to the same thing because one will optimise performance for
an overall window thickness by making the panes parallel. But on the
occasions when a tilted pane is required for whatever reason, your
philosophy will lead to a bigger spacing, or the need for thicker glass for
the same spacing, than mine.

[Angelo Campanella]

Post by Tony

Post by Angelo Campanella
1- The effectiveness in noise isolation strongly depends on the minimum
spacing rather than the maximum spacing in that wedged space. Hence, if
one wants maximum sound attenuation, one spaces the glass surfaces as
far apart as possible.

What's the theoretical basis for that Angelo?
I have always assumed it was
the average spacing that mattered.

Consider a window split down the middle or two windows side by side.
One half has a TL of 50 dB, the other half has a TL of 40 dB. What is
the resulting average TL? It would be 43 dB, closer to the 40 dB half
that to the 50 dB half. The definition of "Average" matters. If you
simply average numerals, you get 45 dB.

You might average sound power expressed in watts. Maybe one-half
picowatt goes through the 50 dB part, while 5 picowatts goes through the
40 dB part, the sum being 5.5 picowatts, nearer the 40 dB window part
than to the 50 dB window part.

Post by Tony
I agree that tilting panes is not effective for improving isolation and is
often counter-productive for reducing light reflections, but it is sometimes
necessary in a low RT room for stopping a flutter echo.

I am only addressing sound transmission. Introducing flutter echoes is
a problem of a third kind. To effectively reduce flutter echoes, tilt
the whole wall. If that's not feasible (e.g. an existing room in an
existing building), then the choice becomes which side pane is more
readily tilted outward. Top? Bottom? Room lamp locations must be
considered. Think it out. That's what you are paid to do. Pane-tilting
on either the vertical or horizontal axis will suit for reducing flutter
echoes.

Post by Tony
Of course, in
practice increasing the average spacing and increasing the minimum spacing
will often come to the same thing because one will optimise performance for
an overall window thickness by making the panes parallel. But on the
occasions when a tilted pane is required for whatever reason, your
philosophy will lead to a bigger spacing, or the need for thicker glass for
the same spacing, than mine.

The designer is obliged to pick a method and to defend that choice in
any way they please. I am only addressing accurately the sound isolation
feature of a window.

Ang. C.

[GregS]

Post by Angelo Campanella

Post by Tony

Post by Angelo Campanella
1- The effectiveness in noise isolation strongly depends on the minimum
spacing rather than the maximum spacing in that wedged space. Hence, if
one wants maximum sound attenuation, one spaces the glass surfaces as
far apart as possible.

What's the theoretical basis for that Angelo?
I have always assumed it was
the average spacing that mattered.

Consider a window split down the middle or two windows side by side.
One half has a TL of 50 dB, the other half has a TL of 40 dB. What is
the resulting average TL? It would be 43 dB, closer to the 40 dB half
that to the 50 dB half. The definition of "Average" matters. If you
simply average numerals, you get 45 dB.
You might average sound power expressed in watts. Maybe one-half
picowatt goes through the 50 dB part, while 5 picowatts goes through the
40 dB part, the sum being 5.5 picowatts, nearer the 40 dB window part
than to the 50 dB window part.

Post by Tony
I agree that tilting panes is not effective for improving isolation and is
often counter-productive for reducing light reflections, but it is sometimes
necessary in a low RT room for stopping a flutter echo.

I am only addressing sound transmission. Introducing flutter echoes is
a problem of a third kind. To effectively reduce flutter echoes, tilt
the whole wall. If that's not feasible (e.g. an existing room in an
existing building), then the choice becomes which side pane is more
readily tilted outward. Top? Bottom? Room lamp locations must be
considered. Think it out. That's what you are paid to do. Pane-tilting
on either the vertical or horizontal axis will suit for reducing flutter
echoes.

Post by Tony
Of course, in
practice increasing the average spacing and increasing the minimum spacing
will often come to the same thing because one will optimise performance for
an overall window thickness by making the panes parallel. But on the
occasions when a tilted pane is required for whatever reason, your
philosophy will lead to a bigger spacing, or the need for thicker glass for
the same spacing, than mine.

The designer is obliged to pick a method and to defend that choice in
any way they please. I am only addressing accurately the sound isolation
feature of a window.

I am curious about the effect of Argon. I suppose it would be slightly better
at reducing sound level.

greg

[Shhhh! I'm Listening to Reason!]

Post by GregS

Post by Angelo Campanella
1- The effectiveness in noise isolation strongly depends on the minimum
spacing rather than the maximum spacing in that wedged space. Hence, if
one wants maximum sound attenuation, one spaces the glass surfaces as
far apart as possible.

What's the theoretical basis for that Angelo?  
I have always assumed it was
the average spacing that mattered.

       Consider a window split down the middle or two windows side by side.
One half has a TL of 50 dB, the other half has a TL of 40 dB. What is
the resulting average TL?   It would be 43 dB, closer to the 40 dB half
that to the 50 dB half. The definition of "Average" matters. If you
simply average numerals, you get 45 dB.
       You might average sound power expressed in watts. Maybe one-half
picowatt goes through the 50 dB part, while 5 picowatts goes through the
40 dB part, the sum being 5.5 picowatts, nearer the 40 dB window part
than to the 50 dB window part.

I agree that tilting panes is not effective for improving isolation and is
often counter-productive for reducing light reflections, but it is sometimes
necessary in a low RT room for stopping a flutter echo.

       I am only addressing sound transmission. Introducing flutter echoes is
a problem of a third kind. To effectively reduce flutter echoes, tilt
the whole wall. If that's not feasible (e.g. an existing room in an
existing building), then the choice becomes which side pane is more
readily tilted outward. Top? Bottom? Room lamp locations must be
considered. Think it out. That's what you are paid to do. Pane-tilting
on either the vertical or horizontal axis will suit for reducing flutter
echoes.

Of course, in
practice increasing the average spacing and increasing the minimum spacing
will often come to the same thing because one will optimise performance for
an overall window thickness by making the panes parallel.  But on the
occasions when a tilted pane is required for whatever reason, your
philosophy will lead to a bigger spacing, or the need for thicker glass for
the same spacing, than mine.

       The designer is obliged to pick a method and to defend that choice in
any way they please. I am only addressing accurately the sound isolation
feature of a window.

I am curious about the effect of Argon. I suppose it would be slightly better
at reducing sound level.

Argon is heavier (more dense) than air. I would expect it generally to
transmit sound more efficiently as a result, but I doubt that it would
be really significant either way.

Here is something I found in a quick search. Argon or other inert
filler gases are not mentioned:

http://www.donyoungwindows.com/faq/sound.asp

This seems to support my assumption:

The use of argon gas fill in IG units improves sound transmission loss
characteristics at higher frequencies, but air-filled units have an
advantage at the lower frequencies associated with traffic noise.
Therefore, OITC is actually better without argon. Again, the tradeoff
with energy-saving goals must be balanced.

http://www.cbpmagazine.com/article.php?articleid=252

[Angelo Campanella]

Post by GregS
I am curious about the effect of Argon. I suppose it would be slightly better
at reducing sound level.

I's a double-edged sword. The density is greater so its acoustic
impedance is greater, but not neary as great as glass. I think the chief
advantage is a slower sound speed, making the frequency a which the
cavity is resonant much lower. Then there is that exotic coincidence
effect. for that, it looks good since the inner (argon) and outer (air)
coincidence frequencies differ, being, I think the major, and only
significant effect. The low frequency difference mentioned by Zekfr is
harder to fathom.

Angelo Campanella

[Asbjørn]

Post by GregS
I am curious about the effect of Argon. I suppose it would be slightly better
at reducing sound level.

I's a double-edged sword. The density is greater so its acoustic impedance
is greater, but not neary as great as glass. I think the chief advantage
is a slower sound speed, making the frequency a which the cavity is
resonant much lower. Then there is that exotic coincidence effect. for
that, it looks good since the inner (argon) and outer (air) coincidence
frequencies differ, being, I think the major, and only significant effect.
The low frequency difference mentioned by Zekfr is harder to fathom.
Angelo Campanella

Argon and some other pure gas fillings in double glazing usually give a
little better insulation in a wide middle frequency range but a little less
insulation at low and high frequencies. It may help against churchbells but
it may be bad for noise from heavy traffic, Harleys and bass intensive
music. An Argon SF6 mix is better for noise insulation but not good for the
rest of the environment.

Asbjørn.
(Switching to news.motzarella.org seems to have solved my previous
newsreader problem.)

[Tony]

Post by dude-guy
I just didn't understand yet (could you please explain this): Why is
that adding a large gap means much? What happens?

(etc)

You have the usual Usenet problem - lots of information, difficult to sort
out what is really likely to matter in practice!

One good source of explanations is the National Research Council of Canada.
Start with http://irc.nrc-cnrc.gc.ca/pubs/cbd/cbd239_e.html.

When you have read that, consider that for the same overall thickness, a
triple pane system will have a higher mass-air-mass resonance frequency than
a double pane system. Generally for the frequencies of sound we are dealing
with in buildings, and the amount of sound insulation we need (bearing in
mind that there is no point in having a window with better sound insulation
than the wall it's in), it is more effective to use a double pane system
than a triple. It is more useful to lower the resonant frequency (bigger
air gap) than it is to raise the rate of increase of attenuation with
frequency (more than two panes). Having said that, the BBC used triple
paned systems in studios for many years, but they were very thick overall,
and I'm sure that all their modern ones use double pane systems.

[Kari Pesonen]

"dude-guy" <***@gmail.com> wrote in message news:e7e663dd-ad15-43b3-91df-***@s50g2000hsb.googlegroups.com...
On 29 Sep., 23:28, "Asbjørn" <***@frisurf.no> wrote:
... clip...

Post by dude-guy
Do you have some equation where you can show me that large distance =
great noise reduction?
I assume this has something to do with standing waves / pipe organ
equations or something, but can someone please explain what happens to
the sound waves, when increasing the distance and why it damps so much
better?

Let's assume that there are no air leaks (paths for airborne
sound propagation) in the window + outer wall.

Indoor noise is caused by the sound radiation from vibrating class
pane surface facing the room. Sound power radiated (W [W]) is a product
of following five variables:
W = rho c sigma <v^2> S, where
rho = density of air (ca. 1,2 kg/m^3),
c = sound speed in air (ca. 340 m/s),
sigma = radiation factor,
<v^2> = pane surface vibration velocity to power 2, average over area
and time [m^2/s^2],
S = area of the pane [m^2].
rho, c and S are (in principle) constants when the area of the window is
fixed.
sigma depends on material - mainly on mass [kg/m^2], bending stiffness and
damping factor - size, and fixing details of the pane.
W, sigma and <v^2> are frequency dependent variable (different
values at different frequencies), rho, c and S are frequency independent.

We can say: the lower the <v^2> at certain incident outdoor noise, the
better the
sound reduction (and STC).

In principle increasing the distance between panes reduce vibration
connection between
panes. This means that <v^2> - as well as W - of the pane facing to the room
is reduced in relation
to <v^2> of the outer pane. If we change only the distance, c, rho, sigma,
and S do not
change. The air space between the panes behaves like a mechanical spring
between the panes.
The longer the spring, the lower the spring constant [N/m].
If we change thickness, mass + bending stiffness + sigma do change
(and damping factor in minor degree).

We may ask why the simple formula above is valid? The dimension of the
product
of the four variables (rho, c, v^2, S) is Watt or the sound power radiated
in time unit.
All other variables (W included), but sigma, can be easily measured.
We can always find a sigma that fulfils the equation (makes both sides
equal).
Quite another issue is the question: how accurately we can estimate sigma in
advance.

The sound energy field radiated by the pane facing the room is usually at
least
at certain frequency areas rotational. This means that sound energy streams
are
curved (compare with liquid flow lines), and there are pane areas that
radiate sound,
and sink areas, that absorb radiated sound back to the vibrating pane.
Sigma depends, among other things, on vorticity or rotationality of the
sound
field radiated.

Usually the incident (outdoor) sound field is time depending (at least,
<v^2> and sigma varies in time), for example due to moving sound sources.
This is why also the phenomena I describe above, are time depending, not
"constant" in time, as is the case in laboratories when sound reduction
(STC) is measured.


all the best

Kari Pesonen

[dude-guy]

Hi Kari,

Sorry for the late answer - I've been very hooked up lately, but this
is really great...

Post by Kari Pesonen
... clip...

Post by dude-guy
Do you have some equation where you can show me that large distance =
great noise reduction?
I assume this has something to do with standing waves / pipe organ
equations or something, but can someone please explain what happens to
the sound waves, when increasing the distance and why it damps so much
better?

Let's assume that there are no air leaks (paths for airborne
sound propagation) in the window + outer wall.

Yep.

Post by Kari Pesonen
Indoor noise is caused by the sound radiation from vibrating class
pane surface facing the room. Sound power radiated (W [W]) is a product

Okay. What's the name of that equation, so I can google it and read
more about it? It's such a shame that latex cannot be used on usenet,
for easier interpretation of equations :-) !

Post by Kari Pesonen
W = rho c sigma <v^2> S, where
rho = density of air (ca. 1,2 kg/m^3),
c = sound speed in air (ca. 340 m/s),
sigma = radiation factor,
<v^2> = pane surface vibration velocity to power 2, average over area
              and time [m^2/s^2],
S = area of the pane [m^2].

Ok, that is the variables.

Post by Kari Pesonen
rho, c and S are (in principle) constants when the area of the window is
fixed.

Agreed. Sigma and v^2 is "variables".

Post by Kari Pesonen
sigma depends on material - mainly on mass [kg/m^2], bending stiffness and
damping factor -  size, and fixing details of the pane.

What's the material property name of Sigma, so I can google for values
(in mech. engineering it is stress or force per area, but I don't
think it is here)?

Post by Kari Pesonen
W, sigma and <v^2> are frequency dependent variable (different
values at different frequencies), rho, c and S are frequency independent.

Ok, I would like to google for some more info on this.

Post by Kari Pesonen
We can say: the lower the <v^2> at certain incident outdoor noise, the
better the
sound reduction (and STC).

Agreed (if "Sigma" is constant).

Post by Kari Pesonen
In principle increasing the distance between panes reduce vibration
connection between
panes. This means that <v^2> - as well as W - of the pane facing to the room

Yes, we would like to show that increasing distances = reducing noise.

But why is it that v^2 is reduced because the distance between panes
is increasing (I'm sure it's correct what you write)?

Post by Kari Pesonen
is reduced in relation
to <v^2> of the outer pane. If we change only the distance, c, rho, sigma,
and S do not
change. The air space between the panes behaves like a mechanical spring
between the panes.
 The longer the spring, the lower the spring constant [N/m].
If we change thickness, mass + bending stiffness + sigma do change
(and damping factor in minor degree).

Ok, I would like to google for more information on the equation. What
was the name of the equation?

Post by Kari Pesonen
We may ask why the simple formula above is valid? The dimension of the
product
of the four variables (rho, c, v^2, S) is Watt or the sound power radiated
in time unit.
All other variables (W included), but sigma, can be easily measured.
We can always find a sigma that fulfils the equation (makes both sides
equal).
Quite another issue is the question: how accurately we can estimate sigma in
advance.

I still don't understand the "sigma"-variable completely - what was
the name of it?

Post by Kari Pesonen
The sound energy field radiated by the pane facing the room is usually at
least
at certain frequency areas rotational. This means that sound energy streams
are
curved (compare with liquid flow lines), and there are pane areas that
radiate sound,
and sink areas, that absorb radiated sound back to the vibrating pane.
Sigma depends, among other things, on vorticity or rotationality of the
sound
field radiated.

uuuh... now it gets complicated...

Post by Kari Pesonen
Usually the incident (outdoor) sound field is time depending (at least,
<v^2> and sigma varies in time), for example due to moving sound sources.
This is why also the phenomena I describe above, are time depending, not
"constant" in time,  as is the case in laboratories when sound reduction
(STC) is measured.
all the best

Thanks. Most importantly, I would like to read more about what you're
writing... If anyone has links to webpages (perhaps with java-
illustrations and such), I would like to be informed about where I can
learn more - just explaining the above in some other words and perhaps
with illustrations...

Thanks!

[dude-guy]

Post by Tony
(sensible suggestions, but only in alt.sci.physics.acoustics)
I've set this back to all the original groups in case the OP isn't reading
alt.sci.physics.acoustics.

Thanks - I wasn't reading that group earlier...

[dude-guy]

Post by Asbjørn

Post by OG

Post by OG

In article

Post by dude-guy
Hope somebody is clever enough to help me find the best solution...

Do you now have a energy double panned window. Thats the first step.

Double Glazing for sound reduction requires a significantly wider gap
than DG for heat loss reduction.

Forgot to add
Mind you I'm not an acoustic engineer so I'm happy to be corrected!

The simple main rule for sound insulation is
The inner and outer layer should be as heavy as possible in kg/m2 (lb/ft2),
and the gap between should be as large as possible.

So plastic/polymers doesn't absorb noise more?

Post by Asbjørn
With windows, that means 8 - 12 mm (1/4 - 1/2") glass on both sides of at
least 50 -150 mm (2 - 6") gap.
Any glass between the inner and outer glas (e.g. the inner glass of a thin
DG) will not contribute.

Why not???

How about plastics/polymers between?

Please explain why extra mass in the middle doesn't help?

Post by Asbjørn
Laminated glass will usually not be worth the extra cost.

Agree.

Post by Asbjørn
Do not forget to seal well around the glass and frames, and close the vents.
May be you also should improve the walls (and ceiling?), with some layers of
gypsum board on board walls, or with at least 50 mm insulation mats behind
on brick or concrete..
But no matter what you do, you will still hear the bells.

Agree - noise level should just be lowered...

[GregS]

Post by OG

In article

Post by dude-guy
Hope somebody is clever enough to help me find the best solution...

Do you now have a energy double panned window. Thats the first step.

Double Glazing for sound reduction requires a significantly wider gap than
DG for heat loss reduction.

Just going by experiance when i experianced new windows in the old house.

How about two sets of doubled glazed separated by a few inches ?

greg

[N:dlzc D:aol T:com (dlzc)]

Post by GregS

Post by OG

In article

Post by dude-guy
Hope somebody is clever enough to help me
find the best solution...

Do you now have a energy double panned
window. Thats the first step.

Double Glazing for sound reduction requires
a significantly wider gap than DG for heat
loss reduction.

Just going by experiance when i experianced
new windows in the old house.
How about two sets of doubled glazed
separated by a few inches ?

You will gain little more by a second double pane... since the
wall is also a transmitter of sound.

My wife gained a bit of thermal insulation and sound deadening by
stapling blankets over certain (exterior) walls, and covering
them with fabric that looked like wall paper.

David A. Smith

[Arny Krueger]

Post by GregS
Do you now have a energy double panned window. Thats the
first step.

Good point. I've seen numerous examples where ordinary vinyl storm windows
do a wonderful job of attenuating ambient noise. The spacing may not be
optimal, but they still work a treat.

[Clyde Slick]

Post by Arny Krueger

Post by GregS
Do you now have a energy double panned window. Thats the
first step.

Good point. I've seen numerous examples where ordinary vinyl storm windows
do a wonderful job of attenuating ambient noise. The spacing may not be
optimal, but they still work a treat.

Listen to Arny, he is the expert on bad
noises emanating from churches.

[GregS]

Post by GregS

Post by dude-guy
Hi,
I desperately need an opinion from someone with a good understanding
of materials or noise reduction in general.
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?
Which transparent material reduces "church bell" sound waves the most?
http://www.altuglas.com
Which frequencies do I need to reduce (freq. of sound from church
bell)?
How about optimal layer thickness of the transparent material?
Hope somebody is clever enough to help me find the best solution...

Do you now have a energy double panned window. Thats the first step.

This dude has not said what he has for windows, types, sizes, etc.

greg

[Mark B]

Post by dude-guy
Hi,
I desperately need an opinion from someone with a good understanding
of materials or noise reduction in general.
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?
Which transparent material reduces "church bell" sound waves the most?
I was told these guys make something that can reduce noise:http://www.altuglas.com
Which frequencies do I need to reduce (freq. of sound from church
bell)?
How about optimal layer thickness of the transparent material?
Hope somebody is clever enough to help me find the best solution...

You should also make sure that the primary window is air tight. If
there are air leaks here they will let in much more noise. This
company makes a great product for sealing existing double hung
windows.

http://www.advancedrepair.com/weather_stripping/easy_stop.htm

M Bagdon

[GregS]

Post by dude-guy

Post by dude-guy
Hi,
I desperately need an opinion from someone with a good understanding
of materials or noise reduction in general.
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?
Which transparent material reduces "church bell" sound waves the most?
I was told these guys make something that can reduce noise:http://www.alt=

uglas.com

Post by dude-guy
Which frequencies do I need to reduce (freq. of sound from church
bell)?
How about optimal layer thickness of the transparent material?
Hope somebody is clever enough to help me find the best solution...

You should also make sure that the primary window is air tight. If
there are air leaks here they will let in much more noise. This
company makes a great product for sealing existing double hung
windows.
http://www.advancedrepair.com/weather_stripping/easy_stop.htm
M Bagdon

My 58 year old house has some really good windows which I am now replacing with
energy efficient ones. For 58 years they still seal pretty well and all the hardware works.
The outer storm window was also a plus. The hard part is ripping out the old
and putting in the new. It takes me around 4 hours work each, and does not include
final trim. I notice on the new windows, there is a resonant range when a person outside
the window is speaking and I hear a kind of hollow sound on the other side. I have 9 windows
to replace and possible bay window. I imagine the resonance changes as the temperatur changes,
and the glass bows in different amounts.

greg

[Tony]

... I notice on the new windows, there is a resonant range when a person
outside
the window is speaking and I hear a kind of hollow sound on the other
side. I have 9 windows
to replace and possible bay window. I imagine the resonance changes as the
temperatur changes,
and the glass bows in different amounts.

This might be the effect of sealed double glazing units (IGU). These have
two fairly thin layers of glass separated by a small air space, so there is
a resonance between the mass of the glass and the springiness of the air
between. The resonance frequency will probably be in the low hundreds of
Hz.

[Shhhh! I'm Listening to Reason!]

Post by dude-guy
Hi,
I desperately need an opinion from someone with a good understanding
of materials or noise reduction in general.
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?

Check what the STC rating for the storm windows is. Here is a good
primer on noise reduction for reducing airport noise, which will
likely be overkill for church bells:

www.macnoise.com/pdfs/home-insulation-program/sound_mitigation_guide_final.pdf
-

Post by dude-guy
Which transparent material reduces "church bell" sound waves the most?

It relates to the STC rating, which measure sound transmission of
windows and doors in general. Glass can be fine if it is thick enough.
The higher the STC rating is, less sound is passed.

Post by dude-guy
I was told these guys make something that can reduce noise:http://www.altuglas.com
Which frequencies do I need to reduce (freq. of sound from church
bell)?
How about optimal layer thickness of the transparent material?
Hope somebody is clever enough to help me find the best solution...

Unfortunately homes also need airflow to function properly. If you
button everything up too tight, you'll end up with unhealthy interior
air and possibly moldy walls. You'll have to strike a balance between
airtight (meaning less sound is transmitted to the interior) and
interior air quality. If you close things too tight up you may need to
retrofit an air-to-air exchanger.

[Shhhh! I'm Listening to Reason!]

On Sep 30, 4:44 am, "Shhhh! I'm Listening to Reason!"

Post by Shhhh! I'm Listening to Reason!

Post by dude-guy
Hi,
I desperately need an opinion from someone with a good understanding
of materials or noise reduction in general.
I live close to a church and the church bell makes extreme loud noise.
The noise is really loud, going through my windows. I want to put an
extra layer of window - obviously it should be transparent. Should
this extra layer be real "window glass" or polymeric/plastic "PMMA"?

Check what the STC rating for the storm windows is. Here is a good
primer on noise reduction for reducing airport noise, which will
www.macnoise.com/pdfs/home-insulation-program/sound_mitigation_guide_...
-

Post by dude-guy
Which transparent material reduces "church bell" sound waves the most?

It relates to the STC rating, which measure sound transmission of
windows and doors in general. Glass can be fine if it is thick enough.
The higher the STC rating is, less sound is passed.

I forgot to add: use a dissimilar thickness of glass (or other
material, but I'd personally probably just stay with glass) from your
prime glass for the storm windows to help reduce resonance.

[dude-guy]

On 30 Sep., 11:44, "Shhhh! I'm Listening to Reason!"

Post by Shhhh! I'm Listening to Reason!

Post by dude-guy
Which transparent material reduces "church bell" sound waves the most?

It relates to the STC rating, which measure sound transmission of
windows and doors in general. Glass can be fine if it is thick enough.
The higher the STC rating is, less sound is passed.

Thanks for introducing the term: "STC".

Post by Shhhh! I'm Listening to Reason!

Post by dude-guy
I was told these guys make something that can reduce noise:http://www.altuglas.com
Which frequencies do I need to reduce (freq. of sound from church
bell)?
How about optimal layer thickness of the transparent material?
Hope somebody is clever enough to help me find the best solution...

Unfortunately homes also need airflow to function properly. If you
button everything up too tight, you'll end up with unhealthy interior
air and possibly moldy walls. You'll have to strike a balance between
airtight (meaning less sound is transmitted to the interior) and
interior air quality. If you close things too tight up you may need to
retrofit an air-to-air exchanger.

Yes, I'm aware of the problem, thanks...