We all know how noise-cancelling headphones work, yes? Process the background noise and put peaks in the troughs and vice versa, cancelling each other.

My questions is, does this actually reduce the sound pressure that the ear is subjected to?

If I am exposed to a noise at 100dB and my noise-cancelling headphones make it comfortable to listen to (so that my perceived sound is maybe 50dB) for long periods, am I still going to suffer ear damage?

you’d be best contacting some associated organisation dealing with industrial deafness i’d say

wookiemeister said:

you’d be best contacting some associated organisation dealing with industrial deafness i’d say

Yeah, the industrial deafness info consists of charts that show sound pressure levels and permissible exposure periods. I can’t find anything that addresses this question.

Rule 303 said:

wookiemeister said:

you’d be best contacting some associated organisation dealing with industrial deafness i’d say

Yeah, the industrial deafness info consists of charts that show sound pressure levels and permissible exposure periods. I can’t find anything that addresses this question.

ultimately you’d need to look at what pressure is reaching the ear drum (dB)

you’ll need to contact them directly – cant hurt

http://electronics.howstuffworks.com/gadgets/audio-music/noise-canceling-headphone3.htm

if they cancel the sound then there is no sound pressure.

ChrispenEvan said:

http://electronics.howstuffworks.com/gadgets/audio-music/noise-canceling-headphone3.htm

Anything particular I should be looking at there?

the answer to your question. it answered it for me.

there could be some subtle damage being done that isn’t being done at the ear drum

ChrispenEvan said:

if they cancel the sound then there is no sound pressure.

Excellent. Where does the energy go? ‘Active’ suppression is much more effective than physically isolating the ear (as ‘passive’ ear protectors do).

Rule 303 said:

ChrispenEvan said:

if they cancel the sound then there is no sound pressure.

Excellent. Where does the energy go? ‘Active’ suppression is much more effective than physically isolating the ear (as ‘passive’ ear protectors do).

turns into heat i’d say

heat i would imagine. cos that is where all energy ends up.

or goes on holiday

ChrispenEvan said:

heat i would imagine. cos that is where all energy ends up.

Do noise-cancelling headphones get hot?

in the scheme of things it would be only a minuscule amount of watts, mini or micro watts even.

ChrispenEvan said:

in the scheme of things it would be only a minuscule amount of watts, mini or micro watts even.

Yeah, hmmm… Seems like a powerful amount of energy when you’re listening to it. Easily enough to deform your rib cage, such that you can feel the short bursts as an impact.

Rule 303 said:

ChrispenEvan said:

heat i would imagine. cos that is where all energy ends up.

Do noise-cancelling headphones get hot?

more heat from heat being trapped around the ear than the energy in the air

Rule 303 said:

ChrispenEvan said:

in the scheme of things it would be only a minuscule amount of watts, mini or micro watts even.

Yeah, hmmm… Seems like a powerful amount of energy when you’re listening to it. Easily enough to deform your rib cage, such that you can feel the short bursts as an impact.

whats the noise source

machine noise with a regular beat is better I think

so how hot to the loudspeakers get?

to=do

in practical terms no hotter than you’d expect wearing anything else over your ears

noise cancelling earphones were originally used by fighter pilots to cut down the roar of air past the cockpit

wookiemeister said:

more heat from heat being trapped around the ear than the energy in the air

Eh?

You can get really good in-ear noise-cancelling earphones these days.

Rule 303 said:

wookiemeister said:

more heat from heat being trapped around the ear than the energy in the air

Eh?

You can get really good in-ear noise-cancelling earphones these days.

if that’s the case not much hotter

you’ll have ways they’ve accounted for heat build up

ChrispenEvan said:

so how hot to the loudspeakers get?

They don’t.

(Some do, but let’s not argue the exceptions)

They’re a frictionless magnetic driver.

the point was that they are a source of sound energy so the inverse square law would put them in the highest energy location and if they don’t get hot the a subject at a distance from them would be receiving less energy and therefore not get hot either.

haven’t had anything to do with them, though installed aviation headset in my header for the UHF radio, added a little momentary TX button (you hold it in to work) on side of them, the headset worked good, had a noise cancelling mic setup maybe I reckon. I got to feel important, someone had to pilot the fucken thing, which I did for many years, involved a lot of low flying.

what you’re talking about is something else i’d expect, probably requiring that external sound as heard by your ears to be kept at a certain level, so you can still hear what’s going on? If that’s the case then the device would have to employ a compressor or limiter. For ear safety such an arrangement would have to also limit the maximum sound pressure reproduced so as not to damage your hearing, otherwise the device if not cancelling properly might produce sound pressures (transient maybe) that could damage your ears. I think one fault mode that’d be possible is high frequency feedback, which might be out of the hearing range but still of a high enough intensity to cause damage.

why don’t you read the link i provided so you have some idea before commenting? i’ve told you this before. try to learn.

>why don’t you read the link i provided so you have some idea before commenting? i’ve told you this before. try to learn.

is that me or what?

they cancel sound so there in no increase in sound pressure. if there is no sound being picked up by them they don’t add any sound. that would defeat the purpose. and yes i was talking to you.

you sound like a rude cunt

and you an opinionated and stupid one. i reckon your sheep have a better brain than you. so fuck off with your dumb shit.

transition said:

you sound like a rude cunt

Maybe he’s just sick of dickheads?

according to the article the system blocks high frequency

the high frequency is blocked by the construction of the headphones and the active part suppresses the low frequency.

Active noise-cancelling headphones can do everything that passive ones can do — their very structure creates a barrier that blocks high-frequency sound waves. They also add an extra level of noise reduction by actively erasing lower-frequency sound waves. How do noise-cancelling headphones accomplish this? They actually create their own sound waves that mimic the incoming noise in every respect except one: the headphone’s sound waves are 180 degrees out of phase with the intruding waves.

Rule 303 said:

We all know how noise-cancelling headphones work, yes? Process the background noise and put peaks in the troughs and vice versa, cancelling each other.

My questions is, does this actually reduce the sound pressure that the ear is subjected to?

If I am exposed to a noise at 100dB and my noise-cancelling headphones make it comfortable to listen to (so that my perceived sound is maybe 50dB) for long periods, am I still going to suffer ear damage?

ChrispenEvan said:

the high frequency is blocked by the construction of the headphones and the active part suppresses the low frequency.

Am I still going to suffer ear damage?

Not at all. But … it depends a bit on the nature of the noise.

We all think of noise as a sine-wave. It isn’t always. Sometimes it’s just a pressure spike. When a steel plate is dropped from a height of two metres or so, when a jet makes a sonic boom, it’s not a sine wave and the noise-cancelling aspect doesn’t help at all, in fact it makes things worse by playing back the pressure spike in reverse. That’s because there’s always a time delay between the noise and the anti-noise.

But if it’s a continuous noise, such as from a motor mower or a rock band, then the sound cancelling is superb. And you get no ear damage. Sound pressure levels are greatly reduced.

A simple rule is that if “it comfortable to listen to” then it’s not doing you damage. A dropped steel plate and a sonic boom would not be comfortable to listen to with noise-cancelling headphones.

Noise cancelling headphones ( at least my ones) have a separate unit that holds a battery , a mic and the electronics so if any sound is converted to heat, it is not generated in the headphones but in the bit that clips onto your shirt or wherever you put it.

FWIW they are brilliant on planes where the engine noise is low frequency.

Rule 303 said:

We all know how noise-cancelling headphones work, yes? Process the background noise and put peaks in the troughs and vice versa, cancelling each other.

My questions is, does this actually reduce the sound pressure that the ear is subjected to?

If I am exposed to a noise at 100dB and my noise-cancelling headphones make it comfortable to listen to (so that my perceived sound is maybe 50dB) for long periods, am I still going to suffer ear damage?

OK, try reconsidering the problem with light instead of sound. A high intensity laser is pointed at a wall; an identical laser (same wavelength and same power output) is pointed at the same spot. If the two beams are in phase (laser light is coherent, so all the peaks and troughs in a beam coincide), the peaks of one match the peaks of the other, and the spot is brighter; if they’re out of phase, though, the peaks of one match the troughs of the other, and no spot appears on the wall. What’s happened to the energy?

Thank you for the answers.

pommiejohn said:

FWIW they are brilliant on planes where the engine noise is low frequency.

Bingo. I’ve always wanted some noise reduction device that works on planes.

Rule 303 said:

Thank you for the answers.

cool we can trash the thread now…

Arts said:

cool we can trash the thread now…

You’re a bit late, but yeah OK, go like hell.

since got some of these for listening music, were given to me for xmas, high quality ones that cup the full ear.

frequency range it cancels of ambient is maybe <200cycles, which they do a good job of, they do though generate a little hiss. They have their own amplifier of course and can generate a staggering volume when cranked up.