[AstralStorm]

About the only way noise cancellation could cause hearing damage is if it caused consistent static pressure in the ear cup. The effects of prolonged exposure to static pressures are not completely researched. If you can detect a weird "pressure" effect, then you might be subject to it. The sensation is somewhat like sticking fingers in your ears or, say, travelling down from stay in the mountains. Such overpressure is also sometimes present in poorly designed in-ear monitors.
 
"High" frequency interference caused by imperfect cancellation is low intensity, so if anything, your hearing should be protected instead.
The high frequencies produced are mostly harmonics of the cancelled waveform.
We're talking -40 dB or less of generated harmonics. Might as well argue that any sound reproduction equipment will cause hearing damage as opposed to listening to live music. (Talking about Bose QC25 here, not anything cheaper and/or worse.)
That said, some poor quality noise cancellation systems may actually generate audible annoying distortion - or the driver's frequency response itself might be poor enough that you get high frequency boost, resonances, other annoying and fatiguing qualities.
 
I risk annoying some people, but most of the noise cancelling headphones are actually mediocre or poor quality, easily heard in passive mode.

 

[bikerboy94]

Any headphone can cause damage. Educate yourself about ear and hearing safety.
http://www.head-fi.org/t/723464/hearing-safety-and-ear-health-thread-a-diary-of-a-ear-health-noob
A good place to start.

 

[SSandDigital]

  Maybe someone with some technical background could answer this. I'm somewhat aware of how the technology works, the headphones let the ambient noise in, along with opposing frequencies in order to "cancel" the outside noise (correct me if I'm wrong). What I'm wondering is if letting both of those sound waves along with the music, whether consciously or unconsciously audible, hit your ears, may be too much and could cause negative hearing effects. Please tell me if I'm way off with understanding this. Also, why do noise canceling headphones sound like your underwater?

 
Hope not.  Just bought Sony's MDR1NC for someone who already has poor hearing.
 
What I do know is hearing loss from headphone use is actually still a debate in medical field, and still being studied.  Majority of hearing loss is more attributed to aging.  And seems treble damages hearing more than loud bass.

 

[AstralStorm]

  Any headphone can cause damage. Educate yourself about ear and hearing safety.

That's not the point of this thread at all. The question was specifically if noise cancelling can be worse.

 

[bikerboy94]

  That's not the point of this thread at all. The question was specifically if noise cancelling can be worse.

It's the whole point. If you play headphones to loud they cause damage. Type of headphone doesn't matter.
It's all about decibels.

 

[DisCHORDDubstep]

It's the whole point. If you play headphones to loud they cause damage. Type of headphone doesn't matter.
It's all about decibels.

again, that's not what its about... It's about if a noise cancelling headphone with no music playing can damage your hearing.

 

[kharisma]

  About the only way noise cancellation could cause hearing damage is if it caused consistent static pressure in the ear cup. The effects of prolonged exposure to static pressures are not completely researched. If you can detect a weird "pressure" effect, then you might be subject to it. The sensation is somewhat like sticking fingers in your ears or, say, travelling down from stay in the mountains. Such overpressure is also sometimes present in poorly designed in-ear monitors.
 

 
Sorry, I know this is a bit of an older thread, but this is what I find interesting- I started looking for any indication that ANR headsets might have a hidden downside, and that comment above piqued my interest. I've used ANR headphones for a while without an issue, but where things got interesting is when I recently started pilot training using the Bose A20 ANR headset. The past couple times I haven't used earplugs underneath, and both times my ears were ringing for quite a time afterward. The last time I went flying was 2 days ago and my ears are still ringing on and off. The interesting thing is that if I just put on the headset by itself in a relatively quiet room, I feel like there is a weird sort of pressure like Astral is describing. I don't notice in the loud environment, but I can't help but wonder if it is still there and is "silently" causing damage and I just don't notice it because of all of the other noise going on.
 
I sat in my living room yesterday and put them on with a pair of normal earplugs on underneath- and I saw on some pilot forums that they recommended this as well. I think I will do this from here on out since the passive plugs do better at blocking high-frequency noise anyway- but really makes me wonder if enough studies have been done on this. 
 
Thanks-

 

[kirkohnstad]

Greetings, 
The long term effects of ANR (Active Noise Reduction) have not been properly studied.  ANR systems operate by directing additional unperceived energy into the head tissues - this may be comparable to cell phones and tumors.
 
Though ANR is functional (and comercially succesful), several european countries have banned thier militaries from adopting non-passive attenuation solutions. 
 
I am a physicist and run a program that produces off shore helicopter helmets with the highest passive sound attenuation. 
Hope this is informative. 

 

[Lord Raven]

  Greetings, 
The long term effects of ANR (Active Noise Reduction) have not been properly studied.  ANR systems operate by directing additional unperceived energy into the head tissues - this may be comparable to cell phones and tumors.
 
Though ANR is functional (and comercially succesful), several european countries have banned thier militaries from adopting non-passive attenuation solutions. 
 
I am a physicist and run a program that produces off shore helicopter helmets with the highest passive sound attenuation. 
Hope this is informative. 

 
That is informative. Can you point to a good passive sound cancelling ear plugs? I am eying on Etymotic ER20, is there anything else better than that?
 
Thanks
LR

 

[AstralStorm]

I wouldn't exactly call ANR delivering unperceived energy. The wave physics involved are quite well understood - what happens is the typical wave cancellation.
The static pressure thing is essentially not being able to cancel near DC and imperfect cancellation potentially generating near-DC products. This is easy to verify.
Properly working ANR should not generate (near-)static pressures and should reduce total SPL delivered - this is measured for actual hearing protection nowadays, but headphones for music listening are not qualified as such. The trick is, many hearing protection or ANR devices are fully sealed - same issue as with earplugs, if you have e.g. a cold, your internal pressure relief mechanisms in the ear might not be enough to equalize pressure. This is shared with all in-ears, most prevalent in custom IEMs esp. silicone ones - and custom earplugs.
Best devices would probably have a manually operated vent just for this case, but I haven't ever seen one used in high protection situations.
 
I've never heard of any kind of ANR ban in EU militaries. These systems are widely used in jet fighters and tank operator hearing protection for example. What has been disallowed are level-dependent (amplitude-sensitive) protection earplugs and earmuffs (especially passive, membrane-based), as the new rules in measuring hearing protection (specifically in shooting) have been changed and they do not meet the protection criteria anymore. (Directive 2003/10/EC.) And no, you never could use ANR alone to reduce gunfire noise - there is no system that acts fast enough and protects against the high frequency peak. Double-protection is required in almost all cases for gun shooting due to the way impulse noise requirements are stated.
 
In fact, the directive almost requires ANR for single device constant noise protection as passive protection is often not enough. (Assuming peak noise is low enough.)
 
As for earplugs, ER20 are pretty good, but custom protectors can be up to 10 dB better. The main important feature of ER20 is that they are flat across sound spectrum, making them more suitable for music. Note that even 20 dB attenuation is a pittance when the sound source is say 120 dB peak and averages > 100 dB SPL. (overly loud concerts skirting the law) Even at the attenuated 80 dB SPL we're talking about limited time of exposure. Also remember that the rated attenuation is an average - your own may be up to 5 dB worse. Custom earplugs do not generally have this problem.
 
For gun shooting, you would need these along with good earmuffs at least - small calibre gunshot easily exceeds 150 dB SPL peak, rifles going up to 170 dB SPL... and maximum allowed peak by EU directive is 137 dB SPL for very good reasons.
Some source for the SPLs: http://www.freehearingtest.com/hia_gunfirenoise.shtml
 
Unfortunately, I do not know of any active hearing protector earplug with "hear through" option - essentially with an active microphone and "push-to-hear". I'd like some recommendations myself for this kind of hardware. (At least 3M makes earmuffs with hear-through, they are not cheap.)
 
Oh, and CIEMs are generally not considered hearing protection in general by law, but esp. silicone ones can be used for this purpose with say 25 dB attenuation, acrylics can be thought as 15 dB attenuation. Foam plugs are generally the highest grade hearing protectors (as far as single protectors go) but they attenuate much more at high frequencies - good for gunshots, not as good for listening to music.
 
(One of the main manufacturers is 3M - Comply foam tips are made of the same foam as their NRR 33 dB soft foam protectors.)

 

[Robertpetry]

 
Unfortunately, I do not know of any active hearing protector earplug with "hear through" option - essentially with an active microphone and "push-to-hear". I'd like some recommendations myself for this kind of hardware. (At least 3M makes earmuffs with hear-through, they are not cheap.)
 

 
Well, I wouldn't consider Bose QC20i's "hearing protector earplugs" but they do have a very effective "hear through" option that includes an active microphone and "Push-to-hear."  These work well for that purpose and Bose calls it "Aware Mode."  Certainly some sound gets in since these do not cover the ear and do not sit deep in the ear canal.  Still, for planes, trains, loud public environments, etc, they work well.  I wouldn't use them at the shooting range though.  
 
I'm sure you're familiar with these but; http://www.bose.com/prc.jsp?url=/shop_online/headphones/noise_cancelling_headphones/quietcomfort_20/index.jsp#currentState=qc20_apple 

 

[mikephonix]

  Greetings, 
The long term effects of ANR (Active Noise Reduction) have not been properly studied.  ANR systems operate by directing additional unperceived energy into the head tissues - this may be comparable to cell phones and tumors.
 
Though ANR is functional (and comercially succesful), several european countries have banned thier militaries from adopting non-passive attenuation solutions. 
 
I am a physicist and run a program that produces off shore helicopter helmets with the highest passive sound attenuation. 
Hope this is informative. 

I have a pair of ANR headphones for travelling (esp. flights), my ears ring every time off the aircraft before I had them , but never after. They are very effective and helpful in noise cancelling, but do not sound as much attractive as those open ones I own.
 
Can you point to a  non-passive attenuation  headphone? I had a quick glance at 3M's sound barriers but that looks awful and they are toooooo tight.

 

[klangmeister]

  Greetings, 
The long term effects of ANR (Active Noise Reduction) have not been properly studied.  ANR systems operate by directing additional unperceived energy into the head tissues - this may be comparable to cell phones and tumors.

 
Ohmygodohmygod, someone is wrong on the internet! (I know, I know...)
 
No, it's not comparable to cell phones and tumors. What unperceved energy are you talking about? The EMI caused by the circuitry?  In many ANC earphones, the circuitry is analog, so the resulting frequencies are pretty low and radiation is near non-existent.
 

Though ANR is functional (and comercially succesful), several european countries have banned thier militaries from adopting non-passive attenuation solutions.

 
And that is relevant how?  The danger in defense use is in malfunctioning equipment and cancellation being "too good", so that you don't hear things you'd otherwise notice (and get shot down etc).
 
 

 

[klangmeister]

 

  Any headphone can cause damage. Educate yourself about ear and hearing safety.

 
That sums it up pretty well.
 
tl;dr: No, ANC headphones don't damage your ears.  It's your brain putting 1 and 1 together and coming up with 3.
 
Long version:
 
A round-up on what's happening and why you're getting a pressure sensation
 
ANC headphones actively reduce the SPL of low frequency sounds (up to around 500-2000 Hz, depending on technology and model) by moving their diaphragms in a way to counteract the pressure changes caused by outside sound waves propagating into the earcup. (By the way you can't really say the drivers are radiating low frequencies because the space (volume) they're working on is too small to radiate sound at the frequencies mentioned above.)
 
Passive noise reduction (by the earcups being in the way) works relatively well above these frequencies so that active cancellation is not necessary. That's a good thing, too, because the circuitry isn't "fast" enough to cancel at those frequencies.
 
So the net effect is you're getting very little low frequencies and maybe a bit more SPL at higher frequencies because passive reduction is not as effective at these higher freqencies.
This massive absence of low frequency sound is pretty unnatural. Without knowing it, you're constantly exposed to some low frequency rumble. And with ANC you don't have that.
 
Now say we increase or lower the pressure of your environment (e.g. you're in a plane that's rising or descending). That pressure acts on your eardrums, it sucks them out or pushes them in. This impairs the motion of your ossicles.  This, in turn, reduces their ability to transmit low frequencies.  In effect, your hearing detects mostly the higher frequencies.  And your brain learns to associate that behavior with "there's pressure on my eardrums". 
 
Does the name "Pavlov" ring a bell?  Because when you put on ANC earphones and consequently don't have low frequency rumble to enjoy, your brain goes "Whoa! That must mean I have pressure on my eardrums!" - that is what it learned.
 
Doing that for an extended period of time can be stressful, as no matter how often your Eustachian tubes open up to relieve that perceived/imaginary pressure, nothing changes.
Side note: The effect is similar in an anechoic chamber, where your eyes tel you that you're in a small room while your ears tell you that you're on a free field. Voilá - your hearing seems impaired (you're not hearing reflections that would be normal in a room) and your brain goes "there must be pressure on my eardrums".
 
So there's no damaging going on. It's psachoacoustics and learned behavior. Some people are affected more than others.
In my experience (acoustics engineer for 15 years), you can get used to it.
 
--------------------
Nitpick: some have mentioned ANC earphones causing DC pressure. People - have you *tried* generating DC pressure with a speaker?  *shakes head*

 

[abm0]

I'd like to weigh in after 4 years of using the discontinued ANC model RP-HC500 from Panasonic:
 
I picked these up to isolate myself from office noise. I quickly found out they were mostly ineffective against voices, so I started playing music to drown out the voices - not particularly loud music, just enough to make the voices harder to understand (the key to removing their distracting effect). I was relatively satisfied with this solution for about 3 years and a half, then as conditions changed around the office I started getting louder conversations happening closer to me more often and again I started looking for better solutions. What I found was an application called ChatterBlocker that offered a variety of "masking" sounds to help make the surrounding voices harder to understand: pink noise, water flowing, winds blowing, birds chirping, unintelligible collective mumbles by multiple male or female voices etc. I started using a customized selection of these sounds through the ANC headphones instead of the music. At first it seemed like a godsend, as it allowed me to completely ignore low-to-moderate levels of office noise, but as I kept using this new solution month after month, the loudest of nearby conversations pushed me to turn the volume higher and higher.
 
During this time I would sometimes notice a high-frequency beep in my ears ("ringing" as some call it, like after hearing a loud blast) right after taking off the headphones. Every time it went away on its own after a while, so I didn't think about it much. Then at some point about 6 months after starting the use of these "masking" sounds, I realized that I had been hearing the ringing for an entire week and it wasn't showing signs of stopping. One week turned to two, to a month, two months... I had tinnitus due to permanent hearing damage (and I still have it).
 
The way I see it is I listened to not-very-loud music + ANC for 3.5 years and had no ill effects, then I turned some "masking" sounds too loud + ANC, and I damaged my hearing and gave myself tinnitus. The damage had nothing to do with ANC and everything to do with keeping things too loud for too long.