[knwtmsyn]

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?

 

[TopCaliber]

Quote:

why do noise canceling headphones sound like your underwater?

The idea is to cancel the noise, not give good audio quality.
 
As for ear damage... I dunno :\ 

 

[Arbite]

A noise canceling headphone simply analyses the sound coming into it, then emits a sound of the same frequency in a different phase. This cases destructive interference in the sound wave. 
 
http://astro-canada.ca/_en/_illustrations/a4313_interference_en_g.jpg
 
This picture explains it.
 
A good way to see this in action is to set up a set of stereo speakers and play a constant tone, then move around the room and listen to the volume difference.

 

[Canadian411]

I used to wear Sennheiser PXC450 at work in average about 4-5 hours a day, at the end of the my ears are numb. 
 
I am not sure it will damage but I didn't like the side effect wearing the noise-canceling headphone, so I ended up getting Denon AH-D7000 with Burson amp to compensate the volume level.
 
I barely wear PXC450, I am planing to use on a plane or train.
 
Happy listening ,,,

 

[IEMCrazy]

Quote:

I used to wear Sennheiser PXC450 at work in average about 4-5 hours a day, at the end of the my ears are numb. 
 
I am not sure it will damage but I didn't like the side effect wearing the noise-canceling headphone, so I ended up getting Denon AH-D7000 with Burson amp to compensate the volume level.
 
I barely wear PXC450, I am planing to use on a plane or train.
 
Happy listening ,,,

 
I've never had that effect from my PXC450's though I've never used them for as long a period of time.   Are you sure the "numbness" wasn't actually heightened sensitivity from being in a sound vacuum so long before returning to normal noise levels?  It's sort of a sensory deprivation treatment....
 
I have no medical background, I couldn't tell you if it definitely doesn't cause ear damage, however, to my knowledge the active noise cancelling technologies were designed not for music but as active ear protection in environments where extremely loud noises would cause hearing loss and ambient sound levels are so nigh that passive ear plugs would not save the ears from damage.  I strongly doubt that a technology designed for medical ear protection would itself lead to ear destruction.
 
Industries that rely on active noise cancelling are things like aircraft maintenance, ground traffic, and cargo loading (where you're literally standing under multiple jet engines at idle, or standing to the side of one revving up to full power for takeoff), rocketry launch area personnel, industrial manufacturing and construction, race car pit crews, etc.  In these industries active noise cancelling is the only thing that stands between you and hearing loss. 
 
I believe for the PXC450's Senn touts that the tech was originally designed for (and almost certainly currently in use as) headsets for pilots.  In those cases, the tech is engaged for far longer than 4 hours a day.  It is their communications set, and their ear protection against cabin engine noise all day every day.  One would have to follow audiologist records for pilot patients to see if it is causing problems.
 
 

 

[shstrang98]

I would think that damage is likely to happen.  Just because noise is "canceled out" doesn't mean that there aren't sounds being produced that are outside our range of hearing but equally damaging.  
 
 Wearing sunglasses that don't filter UV will cause your pupils to open and allow in UV light that will damage your eyes.   Why wouldn't the same happen with audio.

 

[Darkblade48]

 
Quote:

 Wearing sunglasses that don't filter UV will cause your pupils to open and allow in UV light that will damage your eyes.   Why wouldn't the same happen with audio.

 
This analogy doesn't really work; pupils dilate and constrict in response to visible light, not UV light.

 

[IEMCrazy]

 
Quote:

I would think that damage is likely to happen.  Just because noise is "canceled out" doesn't mean that there aren't sounds being produced that are outside our range of hearing but equally damaging.  
 
 Wearing sunglasses that don't filter UV will cause your pupils to open and allow in UV light that will damage your eyes.   Why wouldn't the same happen with audio.

 
My non-medical understanding of eyes is this: Eyes are effectively radiation sensors.  We "see" certain bands of radiation, though the eyes still absorb the bands of radiation our brains do not process.  They're basically  a receptor that pulls in all bands of radiation, while converting only certain bands into electrical signals, and our brains only actually bother interpereting certain limited bands of that.
 
My non-medical understanding of ears is this: Ears are airflow receptors.  There are hairs in the ear tuned to pick up vibrations at very specific frequencies.  Any frequency you can't "hear" means you don't have hairs tuned to that frequency, or the ones you once have are long since damaged beyond use.  We hear a huge range of audio.   Different humans have different range limitations (or stripes of frequencies in the middle that no longer receive due to damage.)  But generally the ear doesn't pick up ultra sub-bass (that can be only felt by the body), and it can't pick up UHF over 20khz or so (but the body may feel it on other hair follicles.  There's a huge debate on that alone.)  Basically if its outside your range of hearing, it can't damage anything because you have no receptors in that frequency range to begin with. Even if there was something do "damage" as a result, if you couldn't hear the sound to begin with, you aren't going to be missing out on any damaged receptor hairs even if they do get damaged....your brain wasn't processing the signal from them.
 
Hearing is damaged by frequency, not as a whole unless you cause actual eardrum damage, which is purely due to force of SPL (or physical object/injury) and is a highly painful affair.  If you didn't hear it, it didn't matter.  There are a good many things in the world that produce sounds outside our hearing range. You just don't notice them because they're outside your hearing range.
 
Remember, noise cancelling tech was designed for hearing PROTECTION first and foremost.  It was integrated into headphones as a convenience item long after it was used as a safety device, and it is a critical safety device for anyone working in loud environments with a constant noise. 
 
I imagine the music coming out of your headphones has far more potential to do real damage to frequencies you can hear than whatever UHF frequencies noise cancelling may or may not be emitting.

 

[Holtie43]

first and for-most, as others have stated, active noise cancelling headphones are designed to protect your hearing.
however i will disagree with what some have said about hearing damage being caused by excessively high frequency.
 
sound is a wave as you all know, it differs from radio waves and light waves (which are electromagnetic)  in that it is actually transferred through the particles in the air as a compression and rarefaction (or higher pressure air followed by lower pressure air)
there are two components to sound waves, the speed of the transition from high pressure to low pressure (frequency) and the amount of air being pushed (volume or amplitude).
as IEMCrazy said, our ears have tiny little receptors tuned to specific frequency ranges to pick up sounds in our audible spectrum. they vibrate when the wave passes over them, and that is how we hear. these receptors can be damaged if too much pressure is applied to them and they vibrate too much.
if our body lacks the receptors to detect extremely high frequencies, then there is nothing there to be damaged, therefore they are harmless (at least to hearing, I'm not a doctor or a scientist lol).
for example we are surrounded by super high and super low frequencies all day every day, from the oscillating LED's in your computer monitors, to the high pitched hum of electricity coursing through transmission lines, i often wonder how irritating all the electronics in my house would be to my dog lol. 
back to the point though, as Arbite showed in his first post, sound waves that possess the exact same frequency but are exactly opposite or 180 degree out of phase will destructively interfere with each other. what that means in terms of noise cancelling headphones is that when the original sound wave is in the mids of its rarefaction, or low pressure phase, the opposing sound wave generated by the headphones is providing the exact right pressure and volume of air to fill that hole, thus eliminating it, likewise when the original wave is in the midst of a compression, the phones are sucking the air out of it to create the low pressure that will oppose it. as long as the headphones never exceed the volume of the original sound then the opposing waves will level out providing essentially dead calm air in your ears. an analogy i suppose would be to think of it as two buckets of water, as one fills with water the other empties at exactly the same rate, but if both of those buckets were emptied into a bathtub at any time in the process there would be exactly one bucket worth of water in the bathtub.
 
a final note is that noise cancelling headphones don't produce UHF frequencies, they don't need to, all they need to do is produce frequencies in the range that a human can hear, maybe with a little overlap on either side for safety.
 
sorry if i got a little carried away with all that. hope it helps.
and i want to clarify that i am not an audiologist or a doctor or an expert of any kind, I'm a humble college engineering student.

 

[shstrang98]

Quote:

 

Quote:
Originally Posted by shstrang98


Wearing sunglasses that don't filter UV will cause your pupils to open and allow in UV light that will damage your eyes. Why wouldn't the same happen with audio.
 
Quote:

This analogy doesn't really work; pupils dilate and constrict in response to visible light, not UV light.

 
Right so my thought was that since there is less visible light the pupils will open more thus letting in un-filtered UV light at the same time.  Since they aren't responding to UV light they're not closing to reduce input.

 

[shstrang98]

I guess there are going to be some brands that do it better than other obviously with BOSE being the worst.   

And I thought noise canceling headphones were done for comfort rather than safety.   
 
Quote:

 
 
My non-medical understanding of eyes is this: Eyes are effectively radiation sensors.  We "see" certain bands of radiation, though the eyes still absorb the bands of radiation our brains do not process.  They're basically  a receptor that pulls in all bands of radiation, while converting only certain bands into electrical signals, and our brains only actually bother interpereting certain limited bands of that.
 
My non-medical understanding of ears is this: Ears are airflow receptors.  There are hairs in the ear tuned to pick up vibrations at very specific frequencies.  Any frequency you can't "hear" means you don't have hairs tuned to that frequency, or the ones you once have are long since damaged beyond use.  We hear a huge range of audio.   Different humans have different range limitations (or stripes of frequencies in the middle that no longer receive due to damage.)  But generally the ear doesn't pick up ultra sub-bass (that can be only felt by the body), and it can't pick up UHF over 20khz or so (but the body may feel it on other hair follicles.  There's a huge debate on that alone.)  Basically if its outside your range of hearing, it can't damage anything because you have no receptors in that frequency range to begin with. Even if there was something do "damage" as a result, if you couldn't hear the sound to begin with, you aren't going to be missing out on any damaged receptor hairs even if they do get damaged....your brain wasn't processing the signal from them.
 
Hearing is damaged by frequency, not as a whole unless you cause actual eardrum damage, which is purely due to force of SPL (or physical object/injury) and is a highly painful affair.  If you didn't hear it, it didn't matter.  There are a good many things in the world that produce sounds outside our hearing range. You just don't notice them because they're outside your hearing range.
 
Remember, noise cancelling tech was designed for hearing PROTECTION first and foremost.  It was integrated into headphones as a convenience item long after it was used as a safety device, and it is a critical safety device for anyone working in loud environments with a constant noise. 
 
I imagine the music coming out of your headphones has far more potential to do real damage to frequencies you can hear than whatever UHF frequencies noise cancelling may or may not be emitting.

 

[ramnkym1971]

I see you wrote a comment on the negative hearing effects could yould please elaberate? are you hearing odd things? when after use of the headphones?

 

[Holtie43]

Ears differ from eyes in that they cannot react to input. Your ears don't have the capability to react to the sounds you are hearing because there are no muscles or anything capable of doing it. They literally just convert the sounds that exist into a signal that your brain can interpret. You can't direct your ears at a sound source like you can with your eyes and a light source.
that said, since your ears can't open or close there is no comparison between sunglasses and noise cancelling earphones.
there are as far as I know, no negative physiological effects associated from noise cancelling earphones. in fact they are used as safety devices in some circumstances. in fact they were probably used as safety devices before anyone thought to use them for commercial music devices.

 

[headgear4me]

I have a question regarding noise-cancelling
headphones , as I have just recently acquired
my first set of noise-canceling headphones. They are Audio-Technica model Ath-Anc7b. I don't know if it is coincidence but are noise - canceling headphones more like to cause headaches and tinnitus? Occasionally as I put them on and I switch them on within in a couple minutes instant tinnitus occurs and also I may get a headache once in a while . Over the years and dozens of sets of iem,over the ear, on ear, over the ear design I have never experienced this before and have learned the lesson of moderate listening volume control irregardless of a particular pairs sensitivity.

All comments welcome , Thanks

 

[tordjansson]

I came to this thread because I'm also worried about the long-term effects of active noise cancellation on my hearing. I have, like some other people here, been experiencing some discomfort after having used active noise canceling headphones for a while which has lead to my search for more information.
 
I do have some experience in digital sound processing (basically writing software for mixing and modulating samples for music playback in games and such) although I'm not an expert in the field.
 
The issue I see with noise cancellation has not been addressed in this thread so far and is related to the fact that it creates high-frequency interference while reducing low-frequency noise. This is caused by the original sound wave (to be canceled) and the cancellation sound wave not overlapping perfectly. When they are slightly out of sync, it can cause interference sound.
 
You can emulate this by loading a sample into a soundeditor, load another copy, invert the phase and offset it a bit. Although they largely cancel each other, you also create some high-frequency noise.
 
My concern is that this high-frequency white noise (still in audible spectrum but psycho acoustically largely covered by other sound waves) could cause damage to your hearing. I don't know enough about medicine or the technical details of various active noise cancellation implementations (maybe some kind of filtering in place to avoid this?), but the comments I have seen so far has not touched this issue at all.
 
It would be good if anyone who knows more about this could elaborate and enlighten the rest of us.