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Active Noise-Canceling Headsets In Server Rooms?
An anonymous reader asks: "Recently I co-located our computer room to a temporary hosting facility. It's a big shop, with everything you could want, along with quite a high dB of background noise. I've no desire to wear those silly little yellow earplugs for several hours when I'm on site there, and standard headsets are such non-IT apparel. Given that technology is the cure to many of todays evils I was wondering if any people had experimented with active noise canceling headphones and has something to say about them. Does anyone use any active noise canceling headsets in a computer room or data facility, and if so how good are they?"
http://www.amazon.com/Sony-MDR-NC50-Noise-Cancelin g-Headphones/dp/B0007N55OQ/sr=8-1/qid=1163179023/r ef=pd_bbs_sr_1/104-1893536-4549558?ie=UTF8&s=elect ronics
The customer reviews pretty much sum them up - I've even got one in there. They do a FANTASTIC job at filtering out our 500 servers, with or without playing music.
they work, are cheap, disposable, sanitary, and only take a few days to get used to wearing for hours every day. I worked in a high noise environment for years, and used the "Ears" brand - they're well worth the initial minor discomfort to have continued good hearing.
Um, No it doesn't. By playing the exact opposite wave, it Destroys the original wave, meaning there is now less intensity.
You obviously have never heard of destructive and constructive interference.
I've owned and sampled various active noise cancellation headphones. At best, I've found them to be good. At worst I've found them totally ineffective.
To attenuate high dB environments, I'd consider the "good" of headphones I've tried to be less than satisfactory, i.e., my subjective evaluation has been about a 10 dB or so drop in levels, good, but if you're looking to get rid of noise these won't do that. If the room is loud enough, I think they'd only lessen the noise to barely acceptable levels.
You mentioned you don't want to wear the silly yellow ear plugs... there are some available in other silly colors. ;-) On the other hand, you aren't likely to be anymore comfortable with headphones on the whole time, and you're going to look no less silly. I've found earplugs to be quite effective, and they're something you can get used to.
If you're looking to "use" headphones, i.e., listen to music, you might consider various ear-canal headphones. I own a pair of those, and aside from the amazing sound quality of the music, I get about a 30dB attenuation of ambient noise. Two birds with one stone. YMMV.
Good luck!
Check out the SAGE sysadmin toolbox page, and scooch down to "What's the scoop on hearing protectors and noise-cancelling headsets?". (The whole damn page is useful, too...)
Carousel is a lie!
A positive 90dB wave, plus a "negitive" opposite of it, will add to zero (If the headphones are perfect, but they are not, so add or subtract a few percent).
Review: (1) + (-1) = 0
Wonder what the public key field is for?
My Philips HN100s (admittedly a rather low-end model) do very little as far as noises from a computer (drive whine, cooling fans, etc.) They're excellent against lower bass frequencies (automotive engine noise, airplane engine noise, lawnmower noise).
Also, wearing circumaural ANC headphones is going to be a lot more annoying than almost-invisible earplugs. The in-ear ANC headsets (like the Philips SHN2500s) are absolutely awful compared to good passive-isolating earphones or good earplugs. In fact, my experience with the SHN2500s was that they added more noise than they removed in most environments.
As far as in-ear passive isolating headphones, I have tried the following:
Sony MDR-EXsomethingorother - Silicone rubber earpieces, with rubber hooks that go over your ears. Extremely uncomfortable and not much isolation. $50
JVC HA-FX33 "Marshmallow" headphones - These STILL don't appear on JVC's website anywhere, and I have only seen them at Wal-Mart stores. $20, decent isolation, pretty comfortable, excellent sound.
Radio Shack "NR-1" noise isolating earphones - Great isolation and comfort, not very good bass response. I keep them around for extreme environments where isolation is more important than bass response and sound quality. $40
I haven't used any of the more expensive in-ear monitors. Shure E2cs and E3cs are popular, as are Westone UM1s and UM2s. The UM1/UM2 appear to use the exact same "Comply" tips as the Rat Shack units, so should have the same isolation and comfort, but hopefully better bass response and sound quality due to better drivers.
For the most extreme enviroments, such as the cabin of a Saab 340 turboprop aircraft, my personal favorite is a combo the Rat Shack in-ears connected to an audio source (laptop or iPod) with the Philips HN100s placed over them. Neither of them alone is sufficient for the interior cabin of a turboprop aircraft.
retrorocket.o not found, launch anyway?
Uh...no.
If you're trying to cancel a 90dB wave, you generate the same 90dB wave, inverted. This means that every particle that receives a sound vibration in one direction receives an equal sound vibration in the opposite direction, resulting in a net movement of zero.
No vibration of the air means no vibration of the eardrum, which means no sound doing its mechanical damage to the moving pieces in your ear, which means no signal doing its neural damage inside your cochlea. Notably, earplugs do exactly the same thing to a lesser degree: they reduce the total transmission of vibration (that's what reducing the amplitude is, after all) into your ear canal.
In both cases, you haven't changed the total amount of energy reaching your ear, it's just that some portion of the kinetic energy (sound) that can damage your ear is now thermal energy that won't.
(Of course, noise-cancelling headphones have widely varying effectiveness in various regions of the audible sound spectrum, and won't do anything to prevent transmission of vibration from other parts of your body into your inner ear - but then, neither will softies)
Reality has a conservative bias: it conserves mass, energy, momentum...
You may not like the stupid yellow foam earplugs, but there are better alternitves. Check out http://earplugstore.stores.yahoo.net/profmusearpl1 .html for instance. The idea is that they are both more comforatble and allow you to hear better even while reducing the volume. All of the musicians I have mixed for LOVE them and I've tried them and found them to be much more comfortable than regular foam plugs. In fact, I find having a large headset on, is uncomfortable for long periods and adds strain to your neck. Check them out, they aren't too expensive. (and I have no affilation with this paticular store, it's just the first site I found)
These are the best portable headphones i've ever used. They're not active noise cancelling, because they're so damn good they dont need to be. Put them in and be amazed. I used them extensively in a large (and very loud) server room and was very VERY impressed with their noise cancelling abilities.
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http://www.shure.com/PersonalAudio/Products/Earph
Oh shit! I forgot to click "Post Anonymously"...
You are absolutely correct. If you don't hear it, the sound isn't activating your inner ear. End of story. The original parent simply got the physics wrong. Even the reply that talked about "spikes" still coming through is wrong, if spikes were coming through you would hear them. Simple as that. And, having used noise cancelling headphones for years now, I can tell you that this simply doesn't happen. When being in noisy environments for a number of hours (say, a 15+ hour flight (well, flights), or in a particularly noisy computer room for a couple of days, I would (in the past) always end up with buzzing ears for days and sometimes a week afterwards (I have a small hearing damage in one of my ears because of an accident when I was young). This problem has gone away after I started using the noise cancelling headphones. (My set is a Sennheiser set, I would love to test Bose but they're hard to get buy (little or no retail), and expensive - so I don't know how good they are. Probably at least as good as Sennheiser, but the latter is the only type I've tried.)
I own several ANC/ENC headsets for use in aircraft. They are abso-friggin-lutely fantastic! The first time I tried one on I was completely sold on it. I was sitting next to a humming Coke machine, flipped the ANC switch, and... silence! My ears have thanked me ever since.
My best headset has a Noise Reduction Rating (passive) of 23 dB, and an active NRR of 20 dB, totalling about 43 dB of noise reduction. To say that you are still being pounded with 90dB of energy sounds implausable given that waves 180 degress out of phase with each other would completely destroy each other--drop two pebbles in the water and watch where the waves interfere with each other, the water will be still. Also, here's a bit of a sales pitch about ANR/ENC technology.
ANC headphones are one solution amongst several. They certainly work, but they're not perfect. Noise cancelation isn't 100%, and depending on model, the range of frequencies they can actually counter may not be effective in your environment. With most of them, you can hear a low volume 'hiss' when they're just canceling noise and not playing music. Also note that the "over the ear" type are more effecive (they provide acoustic as well as active noise cancelation) and usually more comfortable than the less expensive "on the ear" types. Finally, most models have a permenantly connected earphone cable and ALL of them lose some, if not most, effectiveness when the batteries die.
I've tried several sets, and they certainly work at the noise levels and freqs I've encountered in the DC's and computer labs I've had to work in. Also great for air travel - which is what te technology was first developed for.
The cheapest solution are the foam earplugs. They're also generally more effective than ANC at protecting your hearing. They do, however, reduce ALL the sound, so conversation (already difficult) becomes more difficult. "In the ear" headphones (Shure or Etymotic, for example) can give the same level of hearing protection and provide music. Some of them have an external mic you can use to hear people talking. I went to a set of Ety's for air travel and find I can listen to music clearly at very low set volume while blocking out more external noise than the Bose or PlaneQuite active units did.
The "ugly", but possibly best, solution, is a set of over-the-ear hearing protectors as you see on construction sites or shooting ranges. They look kinda silly, but they have great sound attenuation.
Best for you will depend on your needs.
Foams are dirt cheap. Professional grade over the ear types are $20-$50 depending on how nice you want. ANC starts under $20 and goes well over $300. Same with in the ear headphones. Top end Shure units are something like $500.
Figure out what you want to do, and experiment.
Never attribute to malice what can as easily be the result of incompetence...
I've got to second the in-ear canalphone recommendation. For one, they use less power (and don't require their own batteries) as most noise-cancelling phones do (better for portable player life). They have excellent broad-spectrum attenuation -- typically far superior to noise-cancelling. And if you invest in a decent pair (even the $80 Shure e2c's) they'll sound a heck of a lot better than most any noise-cancelling set. If you really step up to the plate, Shure's E5 series or Etymotic Research has some models that will simply blow you away -- Shure's even has a "push to hear" feature that allows you to hear outside noises clearly without removing the phones. And the sound quality on these higher-end models is right up there with the best -- period. The same can't be said for ANY noise-cancelling phones.
Of course you have to get used to having something stuck in your ear....
I'm sensitive to noise and have been using a combination of noise cancellers (Bose QuietComforts are far better than any others that I've tried) and ear plugs to survive noisy air conditioners, the din of "bull pen" cubicle farms, the hum of multi-hour plane trips, the roar of servers in machine rooms, and the rumble of gardeners at work in the early morning hours. Noise takes a big toll on you if you're exposed to it for a long time.
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:)
When my (now) wife moved in with me, she couldn't sleep with my snoring. ): She tried my earplugs which helped with the noise, but was uncomfortable to wear over a long period of time. The problem is that my earplugs were too thick and dense for her much smaller ears. After we shopped around, we found much more comfortable ear plugs for her, and she is a much happier camper.
I went through a whole bunch of earplugs before I settled on the ones that I buy for myself and the ones that I buy for my wife -- you might need to do some searching of your own to find the right combination of noise suppression and long-wearing comfort.
This is the "small" earplug that I get for my wife: http://www.am-safety.com/category.asp?catalog_nam
This is the "big" earplug that I get for myself for maximum noise suppression; http://www.am-safety.com/category.asp?catalog_nam
If you buy noise cancellers, buy good ones. My wife and I tried Sharper Image's $100 ANR folding headphones because they were on sale at 50% off... They were terrible -- they cut the low-frequency noise effectively, but added so much high-frequency hiss that we hated them. The only problem I have with the Bose QC's is they are a bit too fragile for the way I handle portable devices*.
In extreme cases, the ear-plug + ANR combo is great. This is what we do when we're flying across the pond.
* Assurion hates me, heh...
I have tried several active noise reduction headsets for use in single engine piston aircraft, and tried the winners in noisier seats on commercial jets and in data centers.
My biggest lesson relevant to this discussion is the ANR headsets are most effective at low frequencies and relatively ineffective at high frequencies. And my experience with server farms is that the noise is mostly high frequency.
The three most significant heatsets I have tried were the Bose Aviation X (excellent but overpriced), the Bose QuietComfort 2 (works well for adults, best fit for children, not the best ANR), and the Lightspeed QFR-XC (the generic branded versions are cheap - 1/4 the price of a Bose X - excellent passive headsets, and quiet at the low end with ANR turned on). The Lightspeed headset also has an adapter for cellphones or music players.
In data centers I get some funny looks when wearing a Lightspeed headset, but for me it is the best choice since I sometimes have to be on the phone while at the server.
I turn off my hearing aid when I go into my server room.
No, seriously.
Being deaf ain't half bad sometimes.
--Dave