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Thread: Active Noise Reduction Headphone Advice?

  1. #1
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    Default Active Noise Reduction Headphone Advice?

    I'm looking for recommendations for headphones that have active noise cancelling. It seems that the Bose QuietComfort 2 model is best of class, but they cost $299. I tried them out at a Bose Store and they are fantastic, but they are way pricey.

    I have the Sony MDR-NC5 model which is a great improvement over the non-noise cancelling models I've tried, but was wondering what advice you might have, since I want a headset with better noise reduction and better audio fidelity (for use with my MP3 player).

    My main usage is for travel on airplanes where I want the headset to eliminate/reduce the jet noise. and allow my MP3 player to come thru loud and clear.

    Any advice?

  2. #2

    Default Re: Active Noise Reduction Headphone Advice?

    Have you considered things like the Shure E2C? They cancell noise by virtue of being an ear-plug, and they use a lot less battery power to run (besides not needing batteries themselves). They are designed to give excellent sound quality too, and if you are willing to pay a bit more, the E5C gives you two drivers, and a better response over the audible range.

    I assume that the E2C would do you if you are using them for MP3 though.

    Also, if you want to pay less, the Sony MDR-EX71SL is supposed to be good too. A friend has these, and he's really impressed.

    Just a thought.

  3. #3
    Flashaholic* mattheww50's Avatar
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    Default Re: Active Noise Reduction Headphone Advice?

    These devices actually fall into 3 categories. The basic process is active noise cancellation, and there are a number of makes (Sony NC5/NC11/NC20), Panasonice, Jensen, Philips etc that give about 10db for frequencies below 1000Hz. These are usually available for under $100, and are without a doubt the best value in the market. in terms of noise cancellation, these are all about the same, and some can be had for a little as about $30. I happen to like the Philips product, the bigger ear cover gives you a little better passive noise reduction.

    How well you can cancel the noise depends upon how fast you can process the input, and how accurately you can produce the anti-nose at exactly the right phase. 10db corresonds to a phase error of about 6 degrees. 18db is about 2 degrees.

    A great deal of aircraft noise is in fact low frequency rumble, so these actually work very well on jet aircraft Aircraft. Unfortunately 10db is just about worthless on a light piston aircraft.

    The next step up use better processors and better alogorithms. The Bose QC series fall into this category, and they are good for about 16-18db at up to 1000hz.
    Expect to pay $200-$300.

    The last ones get kind of exotic. The mid priced noise cancelling Aircraft headsets like Lightspeed are very similar to the Bose QC technology. The high priced stuff like the Bose X, Telex ANR-1D will run you close to a $1000.
    They add a feature called predictive noise cancellation, and while they typically reduce noise actively by about 18db, they can do far better with predictive cancellation.

    For example if you are flying an aircraft with a 3 bladed prop turning at 2400rpm, there is a huge noise spike from the prop at 120hz, and unless the engine rpm changes suddenly, it will always be there. Over a period of seconds, these top end units will lock onto the prop noise, and nail it to the point that it actually disappears as far as the wearer is concerned. Going from 102db in the cabin to below audio threshold is something that has to be experienced to be believed, in fact the biggest problem people using these headsets often have is remembering to speak up enough to actually activate the intercom! BEtween active cancellation, and passive isolation, these headset can reduce prop noise by more than 50db!

    BTW,earplugs do a very poor job with low frequency. The bind is a lot of percpetion of low frequency is via bone conduction, so an earplug doesn't help much. You really do have to cancel it to make it go away!

  4. #4
    *Flashaholic* bwaites's Avatar
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    Default Re: Active Noise Reduction Headphone Advice?

    Actually, speaking from a medical viewpoint, and as I understand it, you can't actually cancel the bone conduction portion of the noise because noise cancellation depends upon producing a wave in oppositon to a sound before it hits the tympanic membrane. Bone conduction does not depend upon that pathway, (vibration of the membrane) and thus cannot effectively be cancelled. Very low audible frequencies are felt as much as heard, (thats why the car audio guys call it "Slam" after all!) and while NC headphones may help with some noise, I haven't found them particularly helpful for the low frequency jet "roar". Someone may know this better, but my guess is in the 40-50 Hz range, maybe a bit lower.

    They do work GREAT for that 60-500 Hz noise though, as described by mattheww50.

    I've tried all but the highest end NC stuff and like my Etymotic earbuds the best, but they aren't cheap either.

    Just my 2 cents.

    Bill

  5. #5
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    Default Re: Active Noise Reduction Headphone Advice?

    I use the MDR-EX71 plug type headphones to listen to MP3 when I'm taking my inflight rest. I use them everytime I fly and have so far worked very well for me. They are not very expensive anyway since they just work by plugging up your ear from external sounds (no electronics).

  6. #6

    Default Re: Active Noise Reduction Headphone Advice?

    I've tried both the Bose QuietComfort (the old one, recently discontinued) and the Sony EX71 "canalphones".

    I bought 2 sets of those QCs for last Christmas while they were being closed out. Both recipients were very pleased with their performance on planes. I did not try them on a plane myself, but I did use them in a mall and near a somewhat noisy exhaust fan, and they greatly reduced the background noise to where music at a moderate volume would cover it. My feeling is $150 good, but not $300 good.

    EX71s: comfort [img]/ubbthreads/images/graemlins/thumbsup.gif[/img] isolation [img]/ubbthreads/images/graemlins/thumbsdown.gif[/img] The isolation is enough to noticeably reduce background noise, but not to where music at a moderate volume will cover it. On an airplane, I'd bet that the music needs to be turned up to possibly harmful levels. I've heard that the Shure E2Cs are much better at isolation.

  7. #7
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    Default Re: Active Noise Reduction Headphone Advice?

    I have not tried any of them. However, I think that bwaites is correct. I can only make such a judgment based on hearing aids. There are claims that the hearing aids will let you hear the sounds that you want to hear while cancelling out other sounds. Such is pure nonsense. If one is in a crowd, there is no way to cancel the noise of the crowd and still hear voices that which you want to hear. I know several people who have tried it and one told me that he just bought over $5,000 worth of ear plugs.

    It might be that noises on an airplane are of different frequencies from the music, and in that case the phones might improve the listening.

    Jerry

  8. #8
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    Default Re: Active Noise Reduction Headphone Advice?

    I tried the Bose headphones (but I didn't buy them because I didn't feel that the performance justified the price). I did end up buying a pair of Aiwa noise cancelling headphones (CPN6, I think). They're clearly not as good as the Bose, probably due in part to the fact that they don't cover your whole ear like the Bose and probably due to the fact that the Bose has higher-performance circuitry. I think all the consumer-level NC headphones will perform at about the same level (some noise cancellation, some addition of "white noise" type sounds, and moderate fidelity).

    John

  9. #9
    *Flashaholic* bwaites's Avatar
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    Default Re: Active Noise Reduction Headphone Advice?

    The major problem with the Bose and other NC headphones that I tried was that the music reproduction quality was at a level significantly below the level I have come to expect.

    If noise cancellation is the highest priority, they work reasonably well, if sound quality is the more important, they all fall far short of my desired level.

    The in-the-canal phones work best only if you get a good seal. That means you have to clear your canals and ears as you descend and ascend to keep the pressure on each side of the membrane the same, otherwise the pressure differential is exacerbated because you have trapped air in the canal, and that bulges the membrane in or out, decreasing your hearing significantly.

    Over the ear phones don't cause as big a problem with this since they don't seal the canal, but that creates its own problem as ambient noise which may not be cancelled sneaks in.

    I guess there really is no free lunch!!

    Bill

  10. #10
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    Default Re: Active Noise Reduction Headphone Advice?

    Wow Math50, you seem to know a fair bit about them!
    The subject interests me rather closely since for my PhD I'm
    currently working on predicitve control inside aeroplane jet engine nacelles to reduce emitted sound. We don't get anywhere near 50dB reductions in our tests so far, but, who knows, the day might come...[img]/ubbthreads/images/graemlins/cool.gif[/img]

    Olivier

  11. #11
    Flashaholic* mattheww50's Avatar
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    Default Re: Active Noise Reduction Headphone Advice?

    Actually they handle ambient noise below 1khz quite well. The mic that picks up the ambient is actually on the OUTSIDE of the headset, and one of the differences between the low priced stuff and Bose QC series is the Bose and other high end have a mic and processor for each ear piece.

    The problem is the higher the frequency, the more difficult it becomes to cancel the noise.

    The key is correctly inserting the canceling energy, so it needs to be as close to 180 degrees out of phase as possible. At say 100Hz, this isn't all that hard. A wave length is about 10 feet, so the difference in position between the microphone and your ear is about 2 orders of magnitude longer than a wave length.INtheory you can get rid of about 90% of the noise 1- (sin of 3.6 degrees). There are some assumption you can make about 100hz noise however that may allow that figure to be improved upon, and with them you can often get that down to about 1-sin(1 degree), those assumption won't work at higher frequencies however.

    At 1 Khz, the 1.5 inches or so from the microphone to the tympanic membrame is a much larger fraction, 1 Khz is about a 1 foot wave length.
    The distance between the mike and the membrane begins to approach the wavelength, as it becomes impossible to get the phase relationship close enough. The 1 inch is now about 10% of a wavelength, so the best you can do is roughly 1 - sin(36 degrees), in other words about half, and it goes down hill from there.

    At 100Hz, where the noise is coming from doesn't make much difference in the phase difference, at 1Khz it does, and that allows you to make the improvements at the low end. As a result of the physical realities it is pretty hard to do much active cancellation at frequencies about 1Khz, fortunately passive noise control starts to work pretty well in that range.

    As far as music fidelity is concerned, remember that these devices are all derived from the needs of Aircraft crew. Those headsets are designed to do well in the 50-3Khz range, because in speech, that is where all the information is. HIgh Fidelity just isn't useful in the original application (in fact it tends to be a problem). I own a Telex ANR-1D. It does indeed support Stereo. It is a great headset for anyone flying in light aircraft, but I won't even suggest it is high fidelity. It just wasn't designed for that. It was designed to reduce aircraft noise (which is outstanding at), and for talking to other people in the aircaft, speech replication.

  12. #12

    Default Re: Active Noise Reduction Headphone Advice?

    Just thought I'd chime in... If you are looking for a hi-fi option, the earphones from Etymotic Research are really top notch. They block a LOT of sound, and do not require any time to "adjust" to the sound the way the active noise canceling units do, making them really great for riding the train, where there are sudden starts and stops in the sounds. Comfort is very subjective... I can wear them for hours at a time and enjoy them imensley, others can't stand them. They do provide a quality of sound that I have NEVER heard in any of the noise canceling units. They are also SMALL, making them more comfortable (for me, anyway) to wear on the plane when compared to big bulky cans. These are studio monitor quality phones in a package that can block something like 41dB (yes, those are real, verified numbers, not just some manufacturer's made up claims).

    These are REALLY good for air travel and other high-noise applications.

    Sorry to sound like I salesman, I just really Really REALLY like mine... [img]/ubbthreads/images/graemlins/grin.gif[/img]

    Paul

  13. #13
    *Flashaholic* bwaites's Avatar
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    Default Re: Active Noise Reduction Headphone Advice?

    I run Etymotics as well, for the reasons I stated above and second TheFire.

    None of the NC's are close for sound quality, once again as I stated. Matteww50 probably hit the nail on the head when he gave the reason for the difference in sound quality, one was designed as a tool for for professional pilots and military use, the other for the best possible sound quality.

    You makes your choice and you pays your price! For me, that was in ear Etymotics, though Shure also makes good in ears.

    Check out headroom.com for the BEST info about 'phones.

    Bill

  14. #14
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    Default Re: Active Noise Reduction Headphone Advice?

    My criteria was small, on-the-ear style and reasonably priced. I may have stretched the definition of reasonably priced with my latest purchase (see below).

    I started with a $40 NoiseBuster headset and used it for many years of airline travel. The only thing I didn't like was the unpadded headband. It would create a hotspot on top of my head on long flights unless I repositioned it regularly.

    I recently switched to the Sennheiser PXC-250 headset and really like it. It folds nicely and has a padded headband, but costs $100. The one minor annoyance with this headset is that the music input cord is not removable for times when I just want to kill the airplane drone. Some folks complain about the cigar shaped electronics, but it hasn't bothered me.

    I am not capable of judging hi-fi audio quality. Since I use these only in airplanes, it didn't matter to me that much. Both units stop the noise effectively, but the Sennheiser seems to do a slightly better job.

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