[RichD]

A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Why does that cost $40 extra?

--
Rich

[Sylvia Else]

On 20/01/2012 3:20 PM, RichD wrote:
A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Why does that cost $40 extra?

--
Rich

Does it? I think you probably mean that its price is $40 more than the
price of otherwise similar non-noise cancelling headphones.

Why is its price that much higher? Because the vendors think that that
price is the one that maximises their profit.

Sylvia.

[miso]

On 1/19/2012 8:20 PM, RichD wrote:
A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Why does that cost $40 extra?

--
Rich

You stock headphone doesn't have a power amp. For the noise cancelling
to work, it has to have an amplifier in it, so it is more than just
adding a microphone. A good system will have a delay line scheme rather
than just sum an external microphone.

I've had the original NCT headphones. OK, but it used a 9V battery (bad)
and the foam rotted (very bad). I had another brand for a while, but the
amp was noisy.

It is far cheaper just to get some etymotics and not have to cancel
noise in the first place.
http://www.etymotic.com/

The patent expired, so these are much cheaper nowadays. You no longer
have to buy direct either.

No extra battery required since it just blocks the noise rather than
tries to cancel it. It is aLways better to have a good sensor than tweak
a bad design with electronics.

[Spehro Pefhany]

On Thu, 19 Jan 2012 20:20:42 -0800 (PST), RichD
wrote:

A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Why does that cost $40 extra?

I paid more like $150 more-- worth every cent.

[Dick Pierce[_2_]]

On 1/19/2012 11:20 PM, RichD wrote:
A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Well, not quite.

It also includes some signal processing, mixing
capability to properly blend the processed mic
signal with the incoming music signal, amplifiers
to power the headphone drivers themselves, the
mechanical packaging to hold it all together, etc.

Why does that cost $40 extra?

It costs extra because of the signal processing,
mixing capability to properly blend the processed
mic signal with the incoming music signal, amplifiers
to power the headphone drivers themselves, the
mechanical packaging to hold it all together, etc.

[Les Cargill[_4_]]

RichD wrote:
A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Why does that cost $40 extra?

--
Rich

0) Why do you think $40+ is expensive for headphones?

1) there is more to it than that. Ask yourself why the audio
stuff at the beginning of "The Conversation" is Movie Science Fiction
(Scott Dorsey on r.a.p used to go on about this, to my
much-enlightenment ). I have never tried these things because I
don't believe they work.

2) Because that is what people will pay for them.

Guy I went to college with went to work for Evil Corporation "X", and
basically lived on the road for like ten years. Wasn't married, so
he was able to save almost everything he made. The point is that these
are a "travel" item and people who burn through a corporation's travel
budget can offset salary & bonus with such purchases, and the
resulting value to them is higher than for those of us who don't.

That is why the Sky Mall magazine is like it is...

--
Les Cargill

[Doug Freyburger]

Les Cargill wrote:
RichD wrote:

A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

There's more signal processing involved than that.

Why does that cost $40 extra?

2) Because that is what people will pay for them.

In particular they perform a very valuable function. Many people big
distracted by background noise so they can work under more
circumstances. Some people are bothered by certain noises and can't
sleep. There's a long list of such applications.

Guy I went to college with went to work for Evil Corporation "X", and
basically lived on the road for like ten years. Wasn't married, so
he was able to save almost everything he made. The point is that these
are a "travel" item and people who burn through a corporation's travel
budget can offset salary & bonus with such purchases, and the
resulting value to them is higher than for those of us who don't.

There's a guy at the office who wears noise cancelling headphones to be
able to work. He's the second loudest guy in the office when he's not
wearing them but quiet when he's wearing them so everyone benefits.
Well, almost everyone. The reason he wears them is his cubicle is close
to the first loudest guy in the office who's on a completely different
scale than most people. The headphones are literally called "Brian
cancelling headphones" in this case.

That is why the Sky Mall magazine is like it is...

The prices aren't that different in stores for many of their items.

[RichD]

On Jan 20, Les Cargill wrote:
A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Why does that cost $40 extra?

2) Because that is what people will pay for them.

Guy I went to college with went to work for Evil Corporation "X", and
basically lived on the road for like ten years. Wasn't married, so
he was able to save almost everything he made. The point is that these
are a "travel" item and people who burn through a corporation's travel
budget can offset salary & bonus with such purchases, and the
resulting value to them is higher than for those of us who don't.

That is why the Sky Mall magazine is like it is...


Sky Mall magazine?

--
Rich

[RichD]

On Jan 19, RichD wrote:
A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Why does that cost $40 extra?

And with exquisite timing....

http://tinyurl.com/NYT-headphones

My psychic powers amaze me -

(although I was looking at units below $100)


--
Rich

[Les Cargill[_4_]]

RichD wrote:
On Jan 20, Les wrote:
A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Why does that cost $40 extra?

2) Because that is what people will pay for them.

Guy I went to college with went to work for Evil Corporation "X", and
basically lived on the road for like ten years. Wasn't married, so
he was able to save almost everything he made. The point is that these
are a "travel" item and people who burn through a corporation's travel
budget can offset salary& bonus with such purchases, and the
resulting value to them is higher than for those of us who don't.

That is why the Sky Mall magazine is like it is...


Sky Mall magazine?

--
Rich


I gather you don't fly much?

http://www.skymall.com/shopping/homepage.htm?pnr=ING

--
Les Cargill

[HardySpicer]

On Jan 20, 5:20*pm, RichD wrote:
A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Why does that cost $40 extra?

--
Rich

cos that's not what it does! There is a dsp chip in their doing
adaptive noise cancellation.


Hardy

[HardySpicer]

On Jan 20, 5:20*pm, RichD wrote:
A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Why does that cost $40 extra?

--
Rich

You cannot just stick a microphone and invert the signal and hope it
will cancel noise. You need to match the amplitudes at different
frequencies and this requires an adaptive filter.


hardy

[ChrisCoaster]

On Jan 19, 11:20*pm, RichD wrote:
A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Why does that cost $40 extra?

--
Rich
__________
F@(%*# noise-canceling headphones.

-ChrisCoaster

[Mark]

--
Rich

You cannot just stick a microphone and invert the signal and hope it
will cancel noise. You need to match the amplitudes at different
frequencies and this requires an adaptive filter.

hardy

oh really?
are you sure?
have you tried it?

Mark

[Peter Larsen[_3_]]

Mark wrote:

Rich

You cannot just stick a microphone and invert the signal and hope it
will cancel noise. You need to match the amplitudes at different
frequencies and this requires an adaptive filter.

hardy

oh really?
are you sure?
have you tried it?

Literatu Tales from the White Hart.

Mark

Kind regards

Peter Larsen

[Arny Krueger[_4_]]

"Mark" wrote in message
...


--
Rich

You cannot just stick a microphone and invert the signal and hope it
will cancel noise. You need to match the amplitudes at different
frequencies and this requires an adaptive filter.

hardy

oh really?
are you sure?
have you tried it?

It is unreasonable to demand that every truth be supported by personal
experience.

All that is necessary is to look at the technical details of
implementations of products that are effective.

If you are knowledgeable and experienced enough in other areas you can be
fully aware of the difficulty of the task at hand.

IOW, if you have evidence, background knowledge about how systems work, and
are capable of abstract reasoning, you don't need to do *everything*
yourself.

You can actually learn from other's people's experiences.

I've personally been abused and seen many others abused this way by
know-nothings this way for decades. Everytime another charlatan comes out
with a new utterly fantastic claim for a audio tweak, some lame-brain will
tell me that I can't possibly know that the tweak is BS since I haven't run
right out and bought the product and tried it for myself.

I don't need to eat crap to know its crap. The smell and appearance
suffices for me! Your mileage may vary. ;-)

[Dick Pierce[_2_]]

Mark wrote:
--
Rich

You cannot just stick a microphone and invert the signal and hope it
will cancel noise. You need to match the amplitudes at different
frequencies and this requires an adaptive filter.

hardy


oh really?

Really.

are you sure?

Yes. So are a number of professional, experienced
practitioners in the field of active noise cancellation.

have you tried it?

Yes. So have a number of professional, experienced
practitioners in the field of active noise cancellation.

Have you? Are you professional, experienced practitioner
in the field of active noise cancellation? If so, and if
you are claiming something to the contrary, please present
it so that the other professional, experienced practitioners
can evaluate your claims.

--
+--------------------------------+
+ Dick Pierce |
+ Professional Audio Development |
+--------------------------------+

[Mark]

On Jan 23, 11:05*am, Dick Pierce wrote:
Mark wrote:
--
Rich

You cannot just stick a microphone and invert the signal and hope it
will cancel noise. You need to match the amplitudes at different
frequencies and this requires an adaptive filter.

hardy

oh really?

Really.

are you sure?

Yes. So are a number of professional, experienced
practitioners in the field of active noise cancellation.

have you tried it?

Yes. So have a number of professional, experienced
practitioners in the field of active noise cancellation.

Have you? Are you professional, experienced practitioner
in the field of active noise cancellation? If so, and if
you are claiming something to the contrary, please present
it so that the other professional, experienced practitioners
can evaluate your claims.

--
+--------------------------------+
+ * * * * Dick Pierce * * * * * *|
+ Professional Audio Development |
+--------------------------------+

=======================================
there are 3 classes of noise reduction methods

1) passive

2) active / non-adaptive (this is the case we are talking about)
a feedback
b feedforward

3) active / adaptive...
a feedback
b feedforward

all three methods are viable...

#1 passive is most effective against higher frequencies.

#2 active / non- adaptive is simple and most effective against lower
frequencies in a limited space (such as headphones)

#3 is also effective but more complex

consumer noise reduction earphones make use of a combination of
methods #1 and #2

do you think all noise reducing headphones use complex DSP #3 adaptive
techniques?

here is some literature discussing active non adaptive (#2) as well
as active adaptive noise reduction applicable to the context of
headphones...

http://www.ind.rwth-aachen.de/filead...humacher11.pdf


this device is designed to easily implement active but NOT adaptive
noise reduction headphones

http://ics.nxp.com/products/interfac...et/ne58633.pdf

Note, this is a NON ADAPTIVE system. It is LTI.

This system is like an acoustical op-amp where the mic is the summing
junction. The amplitude and phase of the anti-noise is adjusted
automatically (non adaptively) by the negative feedback just like an
op-amp creates a virtual ground. And just like an op-amp if the loop
gain is increased too far, the system will become unstable.


This supports my contention that noise cancellation can be effective
without ADAPTIVE techniques.

And YES I have tried this and YES it works

a comparison of our credentials is irrelevant at this point

thanks

Mark

[Jamie M]

On 1/23/2012 3:39 PM, Mark wrote:
On Jan 23, 11:05 am, Dick wrote:
Mark wrote:
--
Rich

You cannot just stick a microphone and invert the signal and hope it
will cancel noise. You need to match the amplitudes at different
frequencies and this requires an adaptive filter.

hardy

oh really?

Really.

are you sure?

Yes. So are a number of professional, experienced
practitioners in the field of active noise cancellation.

have you tried it?

Yes. So have a number of professional, experienced
practitioners in the field of active noise cancellation.

Have you? Are you professional, experienced practitioner
in the field of active noise cancellation? If so, and if
you are claiming something to the contrary, please present
it so that the other professional, experienced practitioners
can evaluate your claims.

--
+--------------------------------+
+ Dick Pierce |
+ Professional Audio Development |
+--------------------------------+

=======================================
there are 3 classes of noise reduction methods

1) passive

2) active / non-adaptive (this is the case we are talking about)
a feedback
b feedforward

3) active / adaptive...
a feedback
b feedforward

all three methods are viable...

#1 passive is most effective against higher frequencies.

#2 active / non- adaptive is simple and most effective against lower
frequencies in a limited space (such as headphones)

#3 is also effective but more complex

consumer noise reduction earphones make use of a combination of
methods #1 and #2

do you think all noise reducing headphones use complex DSP #3 adaptive
techniques?

here is some literature discussing active non adaptive (#2) as well
as active adaptive noise reduction applicable to the context of
headphones...

http://www.ind.rwth-aachen.de/filead...humacher11.pdf


this device is designed to easily implement active but NOT adaptive
noise reduction headphones

http://ics.nxp.com/products/interfac...et/ne58633.pdf

Note, this is a NON ADAPTIVE system. It is LTI.

This system is like an acoustical op-amp where the mic is the summing
junction. The amplitude and phase of the anti-noise is adjusted
automatically (non adaptively) by the negative feedback just like an
op-amp creates a virtual ground. And just like an op-amp if the loop
gain is increased too far, the system will become unstable.


This supports my contention that noise cancellation can be effective
without ADAPTIVE techniques.

And YES I have tried this and YES it works

a comparison of our credentials is irrelevant at this point

thanks

Mark

Hi,

Is it possible to make active noise cancelling headphones without using
a separate microphone? I was thinking it could be possible to use the
headphones speaker elements as a microphone and sample them, and change
the drive signals accordingly, that could allow normal headphones to be
used as all the electronics would be in the signal source (ie. mp3
player).

cheers,
Jamie

[JosephKK]

On Fri, 20 Jan 2012 13:10:59 -0500, Dick Pierce
wrote:

On 1/19/2012 11:20 PM, RichD wrote:
A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Well, not quite.

It also includes some signal processing, mixing
capability to properly blend the processed mic
signal with the incoming music signal, amplifiers
to power the headphone drivers themselves, the
mechanical packaging to hold it all together, etc.

Why does that cost $40 extra?

It costs extra because of the signal processing,
mixing capability to properly blend the processed
mic signal with the incoming music signal, amplifiers
to power the headphone drivers themselves, the
mechanical packaging to hold it all together, etc.

Where does the energy for all that processing and mixing come from?

?-)

[JosephKK]

On Mon, 23 Jan 2012 16:19:03 -0800, Jamie M wrote:

On 1/23/2012 3:39 PM, Mark wrote:
On Jan 23, 11:05 am, Dick wrote:
Mark wrote:
--
Rich

You cannot just stick a microphone and invert the signal and hope it
will cancel noise. You need to match the amplitudes at different
frequencies and this requires an adaptive filter.

hardy

oh really?

Really.

are you sure?

Yes. So are a number of professional, experienced
practitioners in the field of active noise cancellation.

have you tried it?

Yes. So have a number of professional, experienced
practitioners in the field of active noise cancellation.

Have you? Are you professional, experienced practitioner
in the field of active noise cancellation? If so, and if
you are claiming something to the contrary, please present
it so that the other professional, experienced practitioners
can evaluate your claims.

--
+--------------------------------+
+ Dick Pierce |
+ Professional Audio Development |
+--------------------------------+

=======================================
there are 3 classes of noise reduction methods

1) passive

2) active / non-adaptive (this is the case we are talking about)
a feedback
b feedforward

3) active / adaptive...
a feedback
b feedforward

all three methods are viable...

#1 passive is most effective against higher frequencies.

#2 active / non- adaptive is simple and most effective against lower
frequencies in a limited space (such as headphones)

#3 is also effective but more complex

consumer noise reduction earphones make use of a combination of
methods #1 and #2

do you think all noise reducing headphones use complex DSP #3 adaptive
techniques?

here is some literature discussing active non adaptive (#2) as well
as active adaptive noise reduction applicable to the context of
headphones...

http://www.ind.rwth-aachen.de/filead...humacher11.pdf


this device is designed to easily implement active but NOT adaptive
noise reduction headphones

http://ics.nxp.com/products/interfac...et/ne58633.pdf

Note, this is a NON ADAPTIVE system. It is LTI.

This system is like an acoustical op-amp where the mic is the summing
junction. The amplitude and phase of the anti-noise is adjusted
automatically (non adaptively) by the negative feedback just like an
op-amp creates a virtual ground. And just like an op-amp if the loop
gain is increased too far, the system will become unstable.


This supports my contention that noise cancellation can be effective
without ADAPTIVE techniques.

And YES I have tried this and YES it works

a comparison of our credentials is irrelevant at this point

thanks

Mark

Hi,

Is it possible to make active noise cancelling headphones without using
a separate microphone? I was thinking it could be possible to use the
headphones speaker elements as a microphone and sample them, and change
the drive signals accordingly, that could allow normal headphones to be
used as all the electronics would be in the signal source (ie. mp3
player).

cheers,
Jamie

Not to be too much of a jerk, but just exactly how to you disambiguate the
received noise signal from the reflected corrective signal?

?-)

[Pueblo Dancer]

On Fri, 20 Jan 2012 22:53:12 -0600, Les Cargill
wrote:

RichD wrote:
On Jan 20, Les wrote:
A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Why does that cost $40 extra?

2) Because that is what people will pay for them.

Guy I went to college with went to work for Evil Corporation "X", and
basically lived on the road for like ten years. Wasn't married, so
he was able to save almost everything he made. The point is that these
are a "travel" item and people who burn through a corporation's travel
budget can offset salary& bonus with such purchases, and the
resulting value to them is higher than for those of us who don't.

That is why the Sky Mall magazine is like it is...


Sky Mall magazine?

--
Rich


I gather you don't fly much?

http://www.skymall.com/shopping/homepage.htm?pnr=ING

You can bet that when I do, I am not looking at the damned airline
rags.

I spent $25 on magazines on my last flight to DC. Worth every penny.
Watched a movie off my laptop hard drive too.

[Trevor]

"josephkk" wrote in message
...
Where does the energy for all that processing and mixing come from?

Most commonly, batteries.

Trevor.

[Paul Hovnanian P.E.]

josephkk wrote:

On Fri, 20 Jan 2012 13:10:59 -0500, Dick Pierce
wrote:

On 1/19/2012 11:20 PM, RichD wrote:
A noise canceling headphone consists of a headphone,
plus an external microphone fed to an inverting input,
right?

Well, not quite.

It also includes some signal processing, mixing
capability to properly blend the processed mic
signal with the incoming music signal, amplifiers
to power the headphone drivers themselves, the
mechanical packaging to hold it all together, etc.

Why does that cost $40 extra?

It costs extra because of the signal processing,
mixing capability to properly blend the processed
mic signal with the incoming music signal, amplifiers
to power the headphone drivers themselves, the
mechanical packaging to hold it all together, etc.

Where does the energy for all that processing and mixing come from?

?-)

A battery. Same thing that lights up the little green LED that makes the
cabin crew stop and tell me to shut off my headphones when we take off.

--
Paul Hovnanian
------------------------------------------------------------------
I think you left the stove on.

[Doug Freyburger]

josephkk wrote:
Dick Pierce wrote:
RichD wrote:

Why does that cost $40 extra?

It costs extra because of the signal processing,
mixing capability to properly blend the processed
mic signal with the incoming music signal, amplifiers
to power the headphone drivers themselves, the
mechanical packaging to hold it all together, etc.

Where does the energy for all that processing and mixing come from?
?-)

Each headset comes with its own tiny little self contained thorium
breeder reactor. Part of the cost is in developing them that small, but
most of it was in getting the shielding light enough that the head sets
don't crush you under their weight. ;^)

[Jamie M]

On 1/23/2012 10:03 PM, josephkk wrote:
Not to be too much of a jerk, but just exactly how to you disambiguate the
received noise signal from the reflected corrective signal?


Hi,

Turn off the drive signal and listen periodically, like a sensorless
BLDC motor maybe?

cheers,
Jamie

[JosephKK]

On Wed, 25 Jan 2012 12:34:18 +1100, "Trevor" wrote:


"josephkk" wrote in message
.. .
Where does the energy for all that processing and mixing come from?

Most commonly, batteries.

Trevor.

And could you explain to me how all the battery power gets to headphone
sets that do not contain batteries, nor obtain such power from the base
device? They shrilly claim to be noise canceling headphones as well.

?-)

[JosephKK]

On Wed, 25 Jan 2012 17:12:40 -0800, Jamie M wrote:

On 1/23/2012 10:03 PM, josephkk wrote:
Not to be too much of a jerk, but just exactly how to you disambiguate the
received noise signal from the reflected corrective signal?


Hi,

Turn off the drive signal and listen periodically, like a sensorless
BLDC motor maybe?

cheers,
Jamie


Think that through really carefully. What would be the user response to
that?

?-)

[Jamie M]

On 1/26/2012 11:27 PM, josephkk wrote:
On Wed, 25 Jan 2012 17:12:40 -0800, Jamie wrote:

On 1/23/2012 10:03 PM, josephkk wrote:
Not to be too much of a jerk, but just exactly how to you disambiguate the
received noise signal from the reflected corrective signal?


Hi,

Turn off the drive signal and listen periodically, like a sensorless
BLDC motor maybe?

cheers,
Jamie


Think that through really carefully. What would be the user response to
that?

Hi,

Ok maybe a better idea is to do a continuous FFT of the actual
headphone voltages and then compare this to the "desired" FFT from the
digital audio signal (ie MP3) and then generate a correction signal to
adjust the output voltage.

cheers,
Jamie



?-)

[Jasen Betts[_2_]]

On 2012-01-24, josephkk wrote:
On Mon, 23 Jan 2012 16:19:03 -0800, Jamie M wrote:

Not to be too much of a jerk, but just exactly how to you disambiguate the
received noise signal from the reflected corrective signal?

an amplifier with negative impedance gets you part way there.

--
š‚šƒ 100% natural