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
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.
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.
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.
I paid more like $150 more-- worth every cent.
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.
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.
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
Sky Mall magazine?
-- Rich
And with exquisite timing....
My psychic powers amaze me -
(although I was looking at units below $100)
-- Rich
I gather you don't fly much?
-- Les Cargill
cos that's not what it does! There is a dsp chip in their doing adaptive noise cancellation.
Hardy
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
__________ F@(%*# noise-canceling headphones.
-ChrisCoaster
oh really? are you sure? have you tried it?
Mark
Literature: Tales from the White Hart.
Kind regards
Peter Larsen
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. ;-)
Really.
Yes. So are a number of professional, experienced practitioners in the field of active noise cancellation.
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 |
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D there are 3 classes of noise reduction methods
1) passive2) active / non-adaptive (this is the case we are talking about) a feedback b feedforward
3) active / adaptive... a feedback b feedforwardall 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...
this device is designed to easily implement active but NOT adaptive noise reduction headphones
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
Where does the energy for all that processing and mixing come from?
?-)
it
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
well
Not to be too much of a jerk, but just exactly how to you disambiguate = the received noise signal from the reflected corrective signal?
?-)
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