| Topic: |
Science > Physics |
| User: |
"Canyonland" |
| Date: |
07 Nov 2003 01:18:22 PM |
| Object: |
Noise Cancellation - using only aural tubes |
On my factory floor we use a purely acoustic device, much like a
stethoscope, to speak to the office - everything has to be dielectric.
The tube goes through the glass window and into the noisy factory.
It is only one way communication, as instructions are only passed from
the factory to the office. Our proplem is that as our machinery is
getting louder, the office staff are finding it too noisy when
listening on the tubes.
My question is- How can I modify the tubes so as to eliminate
background noise as much as possible and still allow the voice of the
tube holder to come through to the office ?
I have been researching how directional mics work and other things
like; frequency filters, comb filters and phase cancellation.
Would something like a shotgun mic work? Or, I have heard a more
common approach these days is to have a single tube, with sound entry
ports all the way along it, simulating the effect of many tubes.
We can't use anything electric
or with metal parts, not even small batteries. I was hoping to
overcome this problem, by design with some sort of mechanical noise
reduction... I wonder if this is posible ?
Regards....John
.
|
|
| User: "Uncle Al" |
|
| Title: Re: Noise Cancellation - using only aural tubes |
07 Nov 2003 02:10:48 PM |
|
|
Canyonland wrote:
On my factory floor we use a purely acoustic device, much like a
stethoscope, to speak to the office - everything has to be dielectric.
The tube goes through the glass window and into the noisy factory.
It is only one way communication, as instructions are only passed from
the factory to the office. Our proplem is that as our machinery is
getting louder, the office staff are finding it too noisy when
listening on the tubes.
My question is- How can I modify the tubes so as to eliminate
background noise as much as possible and still allow the voice of the
tube holder to come through to the office ?
I have been researching how directional mics work and other things
like; frequency filters, comb filters and phase cancellation.
Would something like a shotgun mic work? Or, I have heard a more
common approach these days is to have a single tube, with sound entry
ports all the way along it, simulating the effect of many tubes.
We can't use anything electric
or with metal parts, not even small batteries. I was hoping to
overcome this problem, by design with some sort of mechanical noise
reduction... I wonder if this is posible ?
What is the frequency spectrum of the noise as compared to the
voices? A well-chosen foam filter (re earplugs for killing high
freqs) might blank some of the noise and leave the speaking window
intact.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!
.
|
|
|
|
| User: "Bill Vajk" |
|
| Title: Re: Noise Cancellation - using only aural tubes |
07 Nov 2003 08:00:05 PM |
|
|
Canyonland wrote:
On my factory floor we use a purely acoustic device, much like a
stethoscope, to speak to the office - everything has to be dielectric.
The tube goes through the glass window and into the noisy factory.
It is only one way communication, as instructions are only passed from
the factory to the office. Our proplem is that as our machinery is
getting louder, the office staff are finding it too noisy when
listening on the tubes.
My question is- How can I modify the tubes so as to eliminate
background noise as much as possible and still allow the voice of the
tube holder to come through to the office ?
I have been researching how directional mics work and other things
like; frequency filters, comb filters and phase cancellation.
Would something like a shotgun mic work? Or, I have heard a more
common approach these days is to have a single tube, with sound entry
ports all the way along it, simulating the effect of many tubes.
We can't use anything electric
or with metal parts, not even small batteries. I was hoping to
overcome this problem, by design with some sort of mechanical noise
reduction... I wonder if this is posible ?
One used to be able to purchase a small 5 sided box forming
a small anechoic chamber into which a user in a loud factory
setting could place his head and communicate effectively by
telephone. If the product is not commercially available it
isn't very hard to construct one for a few hundred dollars.
There's no reason I can think of that you couldn't put your
sound tube source end into such a chamber with similarly
advantageous effect. I assume the office is trying to listen
to one person speaking, not the entire room.
In the alternative you could attach a microphone to the
recieving end of the sound tube and electronically
reduce the noise very effectively by using fast fourier
transform (FFT) filtering.
In the alternative, you could always hire a lip reader. :-)
.
|
|
|
| User: "Canyonland" |
|
| Title: Re: Noise Cancellation - using only aural tubes |
08 Nov 2003 12:41:26 AM |
|
|
I'm not sure what the frequency spectrum is, but will try some various
types of pvc foam and see how they go. Thanks for the idea.
A 5 sided box wouldn't be ideal for us, but if we can't think of
anything else... cheers.
.
|
|
|
|
|
| User: "Gregory L. Hansen" |
|
| Title: Re: Noise Cancellation - using only aural tubes |
08 Nov 2003 07:20:58 AM |
|
|
In article <6af3fac0.0311071118.3a1f8602@posting.google.com>,
Canyonland <jstreeter@mailandnews.com> wrote:
On my factory floor we use a purely acoustic device, much like a
stethoscope, to speak to the office - everything has to be dielectric.
The tube goes through the glass window and into the noisy factory.
It is only one way communication, as instructions are only passed from
the factory to the office. Our proplem is that as our machinery is
getting louder, the office staff are finding it too noisy when
listening on the tubes.
My question is- How can I modify the tubes so as to eliminate
background noise as much as possible and still allow the voice of the
tube holder to come through to the office ?
I have been researching how directional mics work and other things
like; frequency filters, comb filters and phase cancellation.
Would something like a shotgun mic work? Or, I have heard a more
common approach these days is to have a single tube, with sound entry
ports all the way along it, simulating the effect of many tubes.
We can't use anything electric
or with metal parts, not even small batteries. I was hoping to
overcome this problem, by design with some sort of mechanical noise
reduction... I wonder if this is posible ?
Regards....John
What a wonderfully anachronistic line of communication! Why is it that
there can be no electronics or metal? Even a post-processor inside the
office?
Acoustical circuits have analogs to all kinds of elements in electrical
circuits, like low-pass, high-pass, and notch filters. I remember seeing
some of them described in an old book of acoustics, and it's something
I've been wanting to find a reason to learn about. But I haven't found a
reason yet, so I can't tell you anything about it.
I suppose there must be practical reasons why you don't hang up some
industrial sound-reducing mats in front of the tube. If there's a single
primary source of noise it's fun to think about arranging some reflectors
in just the right place to reduce noise at the tube by destructive
interference, but I'd guess again there are practical limitations to those
sorts of games -- space constraints, etc. There always are.
--
"Let us learn to dream, gentlemen, then perhaps we shall find the
truth... But let us beware of publishing our dreams before they have been
put to the proof by the waking understanding." -- Friedrich August Kekulé
.
|
|
|
|
| User: "John Bailey" |
|
| Title: Re: Noise Cancellation - using only aural tubes |
08 Nov 2003 06:54:13 AM |
|
|
On 7 Nov 2003 11:18:22 -0800, (Canyonland)
wrote:
On my factory floor we use a purely acoustic device, much like a
stethoscope, to speak to the office - everything has to be dielectric.
My question is- How can I modify the tubes so as to eliminate
background noise as much as possible and still allow the voice of the
tube holder to come through to the office ?
Noise cancellation sounds a bit ambitious. An entirely passive system
with noise cancellation sounds like an indirect violation of the
second law. Perhaps you only get a warning not a summons.
In addition to the anechoic chamber and foam filtering suggested
already, you should be able to emphasize the information bearing
frequencies of speech using some combinations of enlargements and
reduction of the pipe so as to attenuate the lows and increase the
resonance of the higher pitched sounds of speech. (I do this when
listening to voice tapes in my van, using its sound system frequency
sliders) Details of how to implement what I am suggesting would
require your doing some research followed by experimentation.
Helmholtz, in his book *On the Sensations of Tone* (which BTW, is
worth reading even if it is over 100 years old) provides a lot of data
on sounds which Helmholtz and others were able to get without
electronics, using resonant chambers etc.
A source for ideas might be the US Patent library. While idiots can
patent totally unworkable schemes, others (the Bose patent for its
compact quality sound system for example) may provide insight into
ways others have used to passively shape the sound spectrum.
John Bailey
http://home.rochester.rr.com/jbxroads/mailto.html
.
|
|
|
|
| User: "Boris Mohar" |
|
| Title: Re: Noise Cancellation - using only aural tubes |
08 Nov 2003 10:46:17 AM |
|
|
On 7 Nov 2003 11:18:22 -0800, (Canyonland) wrote:
On my factory floor we use a purely acoustic device, much like a
stethoscope, to speak to the office - everything has to be dielectric.
The tube goes through the glass window and into the noisy factory.
It is only one way communication, as instructions are only passed from
the factory to the office. Our proplem is that as our machinery is
getting louder, the office staff are finding it too noisy when
listening on the tubes.
My question is- How can I modify the tubes so as to eliminate
background noise as much as possible and still allow the voice of the
tube holder to come through to the office ?
I have been researching how directional mics work and other things
like; frequency filters, comb filters and phase cancellation.
Would something like a shotgun mic work? Or, I have heard a more
common approach these days is to have a single tube, with sound entry
ports all the way along it, simulating the effect of many tubes.
We can't use anything electric
or with metal parts, not even small batteries.
Since the communication is only one way - from the noisy factory floor to the
office than you can use two tubes. One to pickup the background noise and other
to pickup the voice plus noise. Do the subtraction in the office end which I
assume can use electronics. Ask for details in sci.electronics.design
Regards,
Boris Mohar
Got Knock? - see:
Viatrack Printed Circuit Designs http://www3.sympatico.ca/borism/
Aurora, Ontario
.
|
|
|
| User: "Paul R. Mays" |
|
| Title: Re: Noise Cancellation - using only aural tubes |
08 Nov 2003 12:03:16 PM |
|
|
"Boris Mohar" <borism@sympatico.ca> wrote in message
news:437qqv4tc3ng679bftdta2totq7s1ulcpb@4ax.com...
On 7 Nov 2003 11:18:22 -0800, (Canyonland)
wrote:
On my factory floor we use a purely acoustic device, much like a
stethoscope, to speak to the office - everything has to be dielectric.
The tube goes through the glass window and into the noisy factory.
It is only one way communication, as instructions are only passed from
the factory to the office. Our proplem is that as our machinery is
getting louder, the office staff are finding it too noisy when
listening on the tubes.
My question is- How can I modify the tubes so as to eliminate
background noise as much as possible and still allow the voice of the
tube holder to come through to the office ?
I have been researching how directional mics work and other things
like; frequency filters, comb filters and phase cancellation.
Would something like a shotgun mic work? Or, I have heard a more
common approach these days is to have a single tube, with sound entry
ports all the way along it, simulating the effect of many tubes.
We can't use anything electric
or with metal parts, not even small batteries.
Since the communication is only one way - from the noisy factory floor to
the
office than you can use two tubes. One to pickup the background noise and
other
to pickup the voice plus noise. Do the subtraction in the office end
which I
assume can use electronics. Ask for details in sci.electronics.design
Regards,
Boris Mohar
Got Knock? - see:
Viatrack Printed Circuit Designs http://www3.sympatico.ca/borism/
Aurora, Ontario
Close to what I was going to suggest but was thinking of
using a standard noise canceling mic and a destructive
mixer cancellation system to a acoustic coupler to isolate
the shop floor side through a small compressed gas
tube. At the office end the filtered and cleaned audio
is reconstructed...
But for the life of me I can't figure why a fiberoptic
full data / audio high speed communications of on
floor computers, sampling, metering devices to
a central data center is not an option....
Optics would be non conductive and allow multi
channel data ports and hundreds of audio tracks to
have a complete two way handsfree communications
with all others, company and world wide... Could
design a full optical data / voice system with out much
problem with off the shelf components.... Ranging
from a few hundred bucks for a single audio to optical
and back simple device to a Whole bunch of cash for
a true Data / video / audio system with ties to shop
sampling and work systems for data capture and
QC / QS and process control.
I have built several optically based robotic transfer lines
and optically connecting any manufacturing, research or
office systems is actually a much simpler task than
interconnecting and integrating 2 BRIC gantries, 10
Applied Controls cell handlers and all the line
sensors and weld ABC cells.....
With optical in your shop you could automate many
processes and direct all measure, production, status
information on the floor directly to the office where
its just data to be added to reports, statistical software,
inventory control. And total isolation from all EM issues..
and if the cable is a problem, then fix a couple of
laser transceivers through a tiny optically clear class port
in the ceiling somewhere ...
Just a thought....
Paul R. Mays
----------------------------------------------------------------------------
-
Some where within the Quantum State
Http://Paul.Mays.Com/story.html
http://paul.mays.com/mayday.html
http://paul.mays.com/rainy.html
"Science is what you know, philosophy is
what you don't know."
- by Alan Wood
.
|
|
|
|
| User: "Gregory L. Hansen" |
|
| Title: Re: Noise Cancellation - using only aural tubes |
09 Nov 2003 07:31:50 AM |
|
|
In article <437qqv4tc3ng679bftdta2totq7s1ulcpb@4ax.com>,
Boris Mohar <borism@sympatico.ca> wrote:
On 7 Nov 2003 11:18:22 -0800, (Canyonland) wrote:
On my factory floor we use a purely acoustic device, much like a
stethoscope, to speak to the office - everything has to be dielectric.
The tube goes through the glass window and into the noisy factory.
It is only one way communication, as instructions are only passed from
the factory to the office. Our proplem is that as our machinery is
getting louder, the office staff are finding it too noisy when
listening on the tubes.
My question is- How can I modify the tubes so as to eliminate
background noise as much as possible and still allow the voice of the
tube holder to come through to the office ?
I have been researching how directional mics work and other things
like; frequency filters, comb filters and phase cancellation.
Would something like a shotgun mic work? Or, I have heard a more
common approach these days is to have a single tube, with sound entry
ports all the way along it, simulating the effect of many tubes.
We can't use anything electric
or with metal parts, not even small batteries.
Since the communication is only one way - from the noisy factory floor to the
office than you can use two tubes. One to pickup the background noise and other
to pickup the voice plus noise. Do the subtraction in the office end which I
assume can use electronics. Ask for details in sci.electronics.design
Something like this could be done in a purely acoustical way by arranging
the length of the speaker pipe relative to the reference pipe so the noise
is 180 degrees out of phase. But sound covers such a wide range of
frequencies that it would only help if the noise is in a narrow frequency
range. Unless there's some clever way to just reverse the phase of
everything by a reflection or something.
--
"Let us learn to dream, gentlemen, then perhaps we shall find the
truth... But let us beware of publishing our dreams before they have been
put to the proof by the waking understanding." -- Friedrich August Kekulé
.
|
|
|
|
|
| User: "Jan Panteltje" |
|
| Title: Re: Noise Cancellation - using only aural tubes |
08 Nov 2003 09:41:40 AM |
|
|
On a sunny day (7 Nov 2003 11:18:22 -0800) it happened
jstreeter@mailandnews.com (Canyonland) wrote in
<6af3fac0.0311071118.3a1f8602@posting.google.com>:
We can't use anything electric
or with metal parts, not even small batteries. I was hoping to
overcome this problem, by design with some sort of mechanical noise
reduction... I wonder if this is posible ?
Regards....John
Solution is simple, get one of those laser bugging devices, and
have it shine on a little mirror.
You create a mouthpiece and speak to the mirror.
The mirror vibrates, the returned beam is modulated.
Still to much noise from environment?
Connect mirror to your throat (like the old throat mikes).,
and have them beam at that.
Now speak whatever it is, and your voice will be the strongest signal.
I am sort of curious what it is they do so there cannot be a simple
wireless mike?
.
|
|
|
| User: "Paul R. Mays" |
|
| Title: Re: Noise Cancellation - using only aural tubes |
08 Nov 2003 12:05:49 PM |
|
|
"Jan Panteltje" <pNaonStpeAlmtje@yahoo.com> wrote in message
news:1068306146.295899@evisp-news-01.ops.asmr-01.energis-idc.net...
On a sunny day (7 Nov 2003 11:18:22 -0800) it happened
jstreeter@mailandnews.com (Canyonland) wrote in
<6af3fac0.0311071118.3a1f8602@posting.google.com>:
We can't use anything electric
or with metal parts, not even small batteries. I was hoping to
overcome this problem, by design with some sort of mechanical noise
reduction... I wonder if this is posible ?
Regards....John
Solution is simple, get one of those laser bugging devices, and
have it shine on a little mirror.
You create a mouthpiece and speak to the mirror.
The mirror vibrates, the returned beam is modulated.
Still to much noise from environment?
Connect mirror to your throat (like the old throat mikes).,
and have them beam at that.
Now speak whatever it is, and your voice will be the strongest signal.
I am sort of curious what it is they do so there cannot be a simple
wireless mike?
I think they build anti gravitational drive systems for the Army....
But I'm not sure....
.
|
|
|
|
| User: "The Ghost In The Machine" |
|
| Title: Re: Noise Cancellation - using only aural tubes |
08 Nov 2003 06:59:45 PM |
|
|
In sci.physics, Jan Panteltje
<pNaonStpeAlmtje@yahoo.com>
wrote
on Sat, 08 Nov 2003 15:41:40 GMT
<1068306146.295899@evisp-news-01.ops.asmr-01.energis-idc.net>:
On a sunny day (7 Nov 2003 11:18:22 -0800) it happened
jstreeter@mailandnews.com (Canyonland) wrote in
<6af3fac0.0311071118.3a1f8602@posting.google.com>:
We can't use anything electric
or with metal parts, not even small batteries. I was hoping to
overcome this problem, by design with some sort of mechanical noise
reduction... I wonder if this is posible ?
Regards....John
Solution is simple, get one of those laser bugging devices, and
have it shine on a little mirror.
You create a mouthpiece and speak to the mirror.
The mirror vibrates, the returned beam is modulated.
Still to much noise from environment?
Connect mirror to your throat (like the old throat mikes).,
and have them beam at that.
I for one rather like this idea, although aiming the
lasers may be a bit tricky. An alternative may be to use a
plastic cup and a length of string (or monofilament plastic
fishing line); while one may think this is wonderfully
anachronistic one might be able to do something with
the noise at the office end, with any luck, depending on
frequency characteristics of the overall din.
It's also dirt cheap (presumably!), and the string can
be routed through the existing tubes. The main problem
may be whether enough acoustical power can be transmitted
through the string from the office to be heard by the user.
If one wishes, a retracting spring in the office along
with plastic pulleys can be used as well, allowing the
cup and string to be pulled some distance from the wall
during use (which might look a bit odd but as long as
it works); it is not clear to me, however, whether that
will work because of aforementioned noise impinging on the
communications string. The problem does not state whether
one has to worry about hot or acidic things hitting the
string, either (e.g., a metal foundry).
Still another possibility is to simply construct a wooden
phone-style box with closable doors, and mount the tube (or
other such device) inside it. The problem does not state
whether there can be a time delay between the start of a
problem and the reporting thereof to the central office;
there are some political issues here.
(Note that the hinges and screws on such a box would have to
be manufactured out of plastic; this had better be spelled
out in the construction details somewhere, lest someone
screw it up.)
Now speak whatever it is, and your voice will be the strongest signal.
I am sort of curious what it is they do so there cannot be a simple
wireless mike?
Assuming field strengths similar to an NMRI unit in full
operation, a metal wireless mike is a rather bad idea as it
will fling itself towards the source of the magnetic field.
If one is lucky, it will painlessly detach from the neck
of the mike owner first.
I'm not aware of a non-metal wireless mike at this time,
although a diamagnetic or paramagnetic transistor can
might be possible -- but alkaline batteries depend on
metal for their power.
(I'm wondering if their HR screens people out if they have
dental work/fillings? :-) )
--
#191, -- oops, I'm ineligible; too many cavities :-)
It's still legal to go .sigless.
.
|
|
|
|
| User: "Edward Green" |
|
| Title: Re: Noise Cancellation - using only aural tubes |
08 Nov 2003 12:25:20 PM |
|
|
Jan Panteltje <pNaonStpeAlmtje@yahoo.com> wrote in message news:<1068306146.295899@evisp-news-01.ops.asmr-01.energis-idc.net>...
On a sunny day (7 Nov 2003 11:18:22 -0800) it happened
jstreeter@mailandnews.com (Canyonland) wrote in
<6af3fac0.0311071118.3a1f8602@posting.google.com>:
We can't use anything electric
or with metal parts, not even small batteries. I was hoping to
overcome this problem, by design with some sort of mechanical noise
reduction... I wonder if this is posible ?
Regards....John
Solution is simple, get one of those laser bugging devices, and
have it shine on a little mirror.
You create a mouthpiece and speak to the mirror.
The mirror vibrates, the returned beam is modulated.
Still to much noise from environment?
Connect mirror to your throat (like the old throat mikes).,
and have them beam at that.
Now speak whatever it is, and your voice will be the strongest signal.
Congratulations, you get the thinking-outside-of-the-box award.
All other respondents accepted the solution to the problem as
presented, and tried to find solutions to the solution. You went back
to the original problem, and gave an alternate solution.
I liked the idea about passive noise-cancellation getting you a
warning from the second law -- sounds about right. All ideas would
seem to reduce to the simple expedient "increase the signal to noise
ratio": Talking in a box, attenuating unwanted parts of the spectrum,
putting the p/u directly on the throat. We could further split the
application points as the p/u, the medium, and the receiver. You
suggest changing the medium as well as the p/u, and several suggested
changing the receiver (singal post-processing).
How about speaking into a cup on a string!? I think I'm serious:
i.e., substitute a solid member, possibly under tension, for the laser
or the speaking tube. Speaking tubes ... gee ... must be largely a
lost art. Practitioners in the 1880's probably would have had a raft
of tricks up their sleeve for the same problem: communications from
noisy factory floors.
OK ... I guess I have to include an honorable mention for the OTB
award for the person who suggested lip-reading. The _real_ need isn't
even oral/aural communication, but communication. Could also try
semaphore -- or learn morse code? Then you could use a non-conducting
solid medium (stone rod), and tap ... this at least would provide
excellent S/N in the office. You know ... lip reading isn't an
altogether crazy idea: like the laser, it allows a purely optical
link.
.
|
|
|
| User: "Jan Panteltje" |
|
| Title: Re: Noise Cancellation - using only aural tubes |
09 Nov 2003 12:27:07 PM |
|
|
On a sunny day (8 Nov 2003 10:25:20 -0800) it happened
(Edward Green) wrote in <2a0cceff.0311081025.77282706@posting.google.com>:
OK ... I guess I have to include an honorable mention for the OTB
award for the person who suggested lip-reading. The _real_ need isn't
even oral/aural communication, but communication. Could also try
semaphore -- or learn morse code? Then you could use a non-conducting
solid medium (stone rod), and tap ... this at least would provide
excellent S/N in the office. You know ... lip reading isn't an
altogether crazy idea: like the laser, it allows a purely optical
link.
Yes occured to me too, get camera, with glassfiber optic extension (how long
can that be?) fed ino that room.
Then write on piece of paper, hang in front of the glassfiber.
String to ring a bell.
Bell rings, office looks at monitor, done.
Of cause when you have a real window and can lipread, you can just stick a
piece of paper on it too.. very quiet.
.
|
|
|
|
|
|
|
Related Articles |
|
|
