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Sound cancellation technology?

  • Thread starter Voice of freedom
  • Start date
V

Voice of freedom

Jan 1, 1970
0
How far has sound cancellation technology come, for use in a room area? For
example, for a bedroom?

I need some sound cancellation in the bedroom due to street noises outside
while I'm trying to sleep.

I know they have it inside closed headsets for pilots etc, but is the
technology viable yet for a closed room sized area like a bedroom?
 
L

Luhan Monat

Jan 1, 1970
0
Voice said:
How far has sound cancellation technology come, for use in a room area? For
example, for a bedroom?

I need some sound cancellation in the bedroom due to street noises outside
while I'm trying to sleep.

I know they have it inside closed headsets for pilots etc, but is the
technology viable yet for a closed room sized area like a bedroom?

No, and (for all practical purposes) it never will be. Headphone
devices 'muffle' the higher frequecies while 'cancelling' the lower
ones. But this only works with headphones.
 
@

_@_._

Jan 1, 1970
0
Voice of freedom wrote:

[snip]

I have the answer you seek, , but I don't answer questions
that are posted to the wrong places. You posted to:

sci.electronics.misc
..misc newsgroups are for posts that don't fit anyehere else.
This post does fit somewhere else, so it shouldn't be posted
to sci.electronics.misc.

sci.electronics.equipment
Possibly OK, depending on what you are asking for. If you
want an existing piece of equipment, your post belongs in
sci.electronics.equipment but not in sci.electronics.design.
If you want to design something or have something designed,
your post belongs in sci.electronics.design but not in
sci.electronics.equipment.

misc.industry.electronics.marketplace
..marketplace newsgroups are for posts advertising things for
sale. You aren't selling anything, so you post does not belong
in misc.industry.electronics.marketplace

sci.electronics.design
Possibly OK, depending on what you are asking for. If you
want an existing piece of equipment, your post belongs in
sci.electronics.equipment but not in sci.electronics.design.
If you want to design something or have something designed,
your post belongs in sci.electronics.design but not in
sci.electronics.equipment.
 
R

Roger Johansson

Jan 1, 1970
0
Robert said:
If you do not mind experimenting, you might see if you can get a
surplus headset that has the cancelling technology, along with as
much technical info as possible. One or two microphones placed
outside

That is the original idea. But I have heard that it works even better
to put the reference mic inside the headphone, and apply negative
feedback to make the sound inside follow the sound you want, whether it
is music or silence.

That way it doesn't matter what the outside noise is, everything which
is not exactly the wanted sound is cancelled.

Simply apply negative feedback from the mic to make sure that the sound
inside is exactly silence, that will automatically cancel any
disturbancies, whether electronic or acoustic in origin. It is similar
to the motion feedback system Philips used in loudspeakers once. It
forces the sound in front of the loudspeaker to be an exact copy of the
sound signal you want, or silence if that is the result you want.


Talking about the problem in general terms and in rooms also:

You need a passiv screen between the ear and the noise, which dampens
the treble sounds and makes it a lot easier to apply electronic noise
cancelling. In a room this screen can be the walls, in a headphone this
screen is the outer plastic material. Heavy cloth materials dampen
sound well.

The problem is more difficult in a room or apartment, if you want to
cancel noise no matter where you are in the room.
It is easier to cancel noise electronically for a listener in a certain
position in the room.

In a room it can be enough to play some own music, to avoid total
silence, which make the ears more sensible for occasional noise from
outside.
 
R

René

Jan 1, 1970
0
If you have some kind of network with contacts to sound engineers in
opera houses, sound stages, etc, do not hesitate to ask if any "exotic"
technology is used; and for help.

I use earplugs with great succes..
 
R

Ray L. Volts

Jan 1, 1970
0
Voice of freedom said:
How far has sound cancellation technology come, for use in a room area? For
example, for a bedroom?

I need some sound cancellation in the bedroom due to street noises outside
while I'm trying to sleep.

I know they have it inside closed headsets for pilots etc, but is the
technology viable yet for a closed room sized area like a bedroom?


Simpler, more effective, and most importantly, currently available:

http://www.soundproofwindows.com/
 
V

Vidar Løkken

Jan 1, 1970
0
Don said:
The limitations are not in the technology. It is just a physics thing
- you can't cancel sound in volumes larger than a fairly small
fraction of a wavelength.

Please, I'd like some refferences on that. The tests I've conducted (two
4" speakers 1kHz in a Y-shaped pipe) suggest that it can cancel _pretty_
loud sounds. I don't know what signal level I ran at, but it was at
least hearable 30m from the source. When I fed the speakers with
opposite waveforms, they canceled out, and only a slight hum could be
heard. I guess this hum was the vibrations in the mount for the speakers.
 
V

Vidar Løkken

Jan 1, 1970
0
Don said:
This experiment has nothing to do with cancellation in a room. Take
the speakers out of the pipe and try again. Use broadband noise as
your sound, and see what you can achieve by way of cancellation.
Mainly find out how far apart you can place the speakers and still
achieve useful results.

Well, I can't see how not. If you manage to place them according to the
noise, you should get the same effect, if using a DSP that calculates
the waveform, and timing.
Mercedes used this on some of their cars to cancel out noise, and many
planes use it...
 
D

Dave Fase

Jan 1, 1970
0
I sold and installed the Headsets, Inc. Active Noise Reduction (ANR) kits to
pilots for a while back in the mid nineties. Kept up with the advances back
then. If I recall correctly, Bose Laboratories in Boston was experimenting
with "whole aircraft cabin" ANR systems, and that some Business Aircraft
manufacturers were offering Bose's ANR option to anyone who could afford it.
The option was expensive, requiring a number of well placed speakers, a fair
amount of electronics, and extracting some useful load. For reference,
refer
to indices of the SAE publication "Aerospace" from the mid to late nineties.
I think I also recall that someone was building similar ANR systems for OTR
Trucks.

Recollections aside, in my opinion, ANR equipped headsets were, and are a
real plus while flying in general aviation aircraft. Most systems I tried
cancelled much of the lower frequency engine and exhaust noise, and certain
components of slipstream noise. The design and shell of the headset earcups
knock down much of the higher frequency components. All of which makes
for a more relaxing, less tensing flight. A bedroom sized system might work
similarly well for lower frequencies, but I doubt there would be much
protection from higher frequency components such as sirens, plant whistles,
and the like. Just like the earcup shells on a headset, one would probably
need
to super-insulate the walls of the bedroom. One problem which was dominant
with all systems was a "hiss", almost like "white noise". This could be a
bigger
problem on a room or cabin sized ANR system.

Hope that helps to answer the original question. Aloha, Dave
 
V

Voice of freedom

Jan 1, 1970
0
Robert Baer said:
Systems have been built in large halls to get rid of un-wanted echos
as well as enhance the on-stage performance.
I understand that some of these systems are dynamic, so that sounds
from one part of the stage are processed differently than others.
That said, it would seem to be very possible to achieve at least
reasonably acceptable results.
If you do not mind experimenting, you might see if you can get a
surplus headset that has the cancelling technology, along with as much
technical info as possible.
One or two microphones placed outside - say one mounted on cushions
so that it only picks up sounds in the air, and the other mounted near
the base of the wall nearest to the traffic so that it pickups sounds by
"conduction" from the wall (and not by air).
These mikes are the "reference" noise pickups; the waveforms would be
processed before feeding to speakers inside the house/bedroom.
Mostly the lower frequencies are the culprit, so some of the
processing would appear to be possible via filtering.
The basic idea is that the sounds from the indoor speakers are "EQ"
in both amplitude and phase across the spectrum of interest - to cancel
the sound that is transmitted via air thru windows and walls, and cancel
sound conducted via wall and earth movements (truck rolls by).
The "air" reference is processed for the first part, and the
"conducted" reference is processed for the second part.

I use the word "processed" on purpose, as a DSP might be necessary to
achieve optimum results.
The surplus noise cancelling headphones may or may not have a DSP,
depending on how new it is; one would try using two - one for each of
the "channels" i mentioned.

If you have some kind of network with contacts to sound engineers in
opera houses, sound stages, etc, do not hesitate to ask if any "exotic"
technology is used; and for help.

Your name is Rube Goldberg?
 
V

Voice of freedom

Jan 1, 1970
0
Vidar Løkken said:
Please, I'd like some refferences on that. The tests I've conducted (two
4" speakers 1kHz in a Y-shaped pipe) suggest that it can cancel _pretty_
loud sounds. I don't know what signal level I ran at, but it was at
least hearable 30m from the source. When I fed the speakers with
opposite waveforms, they canceled out, and only a slight hum could be
heard. I guess this hum was the vibrations in the mount for the speakers.

Yes, I've heard that some experimenters have come pretty close to being able
to do very simple sound cancellation in a room area, without headphones, but
not close enought to produce a perfect product to sell. High speed DSP was
mentioned.
 
V

Voice of freedom

Jan 1, 1970
0
Ray L. Volts said:
Simpler, more effective, and most importantly, currently available:

http://www.soundproofwindows.com/

I already have double windows, which helps some, but the place across the
street is running some kind of home shop business and fills up their
dumpsters a couple of times a week, then calls for pickups. The garbage
truck is a big diesel rumbling thing and that wakes me up, right through
the walls etc.
 
C

Clarence_A

Jan 1, 1970
0
"Voice of freedom" wrote
"Ray L. Volts" wrote :

I already have double windows, which helps some, but
the place across the street is running some kind of
home shop business and fills up their dumpsters a
couple of times a week, then calls for pickups.
The garbage truck is a big diesel rumbling thing
and that wakes me up, right through the walls etc.

Unless you sleep during the day, check the Noise abatement
regulations and file a complaint.

If you sleep during the day Move! It's cheaper.
 
B

Ben Bradley

Jan 1, 1970
0
In
sci.electronics.misc,
sci.electronics.equipment,
misc.industry.electronics.marketplace and
sci.electronics.design,
I already have double windows, which helps some, but the place across the
street is running some kind of home shop business and fills up their
dumpsters a couple of times a week, then calls for pickups. The garbage
truck is a big diesel rumbling thing and that wakes me up, right through
the walls etc.

The next technical step would be a "room within a room" which is of
course a large cost in labor and building materials. It would need to
be built on a floating floor, with the walls and ceiling built on top
of it without touching the existing walls and ceiling. Read F. Alton
Everest's "Master Handbook of Acoustics" if you consider doing this.

Do as Clarence suggested and look for some local noise ordnances
they might be violating, in addition to running a business in a
residential area which might also go against some ordnance, but at
least be a good neighbor, explain the problem to them and give them a
chance to fix it before turning them in for anything.
 
D

Don Taylor

Jan 1, 1970
0
Dave Fase said:
Recollections aside, in my opinion, ANR equipped headsets were, and are a
real plus while flying in general aviation aircraft. Most systems I tried
cancelled much of the lower frequency engine and exhaust noise, and certain
components of slipstream noise. The design and shell of the headset earcups
knock down much of the higher frequency components.
....

One quick question, having tried three brands of noise cancelling
headsets, all three seem to do a good job at reducing low frequency
noise like the roar and rumble inside city busses, engine noise,
etc. But that just brings out the conversations that would otherwise
be buried by the roar.

Strictly dealing with headsets for this question, is not also
cancelling voice/music by design, by limitations of physics, by
limitations of processing power, by limitations of battery power
or by cost of components?

On related notes, but not wanting to derail answers to my question,
perhaps a decade ago I was sitting in a class where the prof claimed
that he had direct knowledge that the Cadillac NorthStar was named
NorthStar because N S recognized that they had built Noise Suppression
and noise cancellation into this car line. I was interested in
this and contacted Cadillac about this at the time. They responded
that this was not the case. We never could resolve this contradiction.

Since that time we have seen advertisements by the companies selling
trucks to the public, describing how much work they put into making
the sound of their trucks make it clear that the owner has really
really large male equipment.
 
L

Luhan Monat

Jan 1, 1970
0
I already have double windows, which helps some, but the place across the
street is running some kind of home shop business and fills up their
dumpsters a couple of times a week, then calls for pickups. The garbage
truck is a big diesel rumbling thing and that wakes me up, right through
the walls etc.

Try the active sleeping ingredient in Bacardi.
 
P

Pooh Bear

Jan 1, 1970
0
Voice said:
How far has sound cancellation technology come, for use in a room area? For
example, for a bedroom?

I need some sound cancellation in the bedroom due to street noises outside
while I'm trying to sleep.

I know they have it inside closed headsets for pilots etc, but is the
technology viable yet for a closed room sized area like a bedroom?

Basically undoable.

Get extra glazing installed.


Graham
 
P

Pooh Bear

Jan 1, 1970
0
Robert said:
If you have some kind of network with contacts to sound engineers in
opera houses, sound stages, etc, do not hesitate to ask if any "exotic"
technology is used; and for help.

As a sound engineer amongst my various skills, please note you're talking out of
your arse.


Graham
 
P

Pooh Bear

Jan 1, 1970
0
Voice said:
I already have double windows, which helps some,

Considered triple glazing ?

Increasing the thickness / weight of the glass is hugely effective too. My
windows are single glazed but with 6mm laminatated glass. Made an astonishing
difference over the old windows.
but the place across the
street is running some kind of home shop business and fills up their
dumpsters a couple of times a week, then calls for pickups. The garbage
truck is a big diesel rumbling thing and that wakes me up, right through
the walls etc.

If it's coming through the walls that's not good. What's your wall
construction ?


Graham
 
P

Pooh Bear

Jan 1, 1970
0
Don said:
Since that time we have seen advertisements by the companies selling
trucks to the public, describing how much work they put into making
the sound of their trucks make it clear that the owner has really
really large male equipment.

It could only happen in the USA ! Lol ! Do they fit machine guns too on request ?



Graham
 
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