how does active noise cancellation works and is it more harmful to your ears than normal headphones or earphones
In: Technology
No, it’s not harmful. Noise cancelling headphones just play a tone that cancels out the noise around you. How does it work?
Picture a sound wave, with peaks and valleys, coming out of a speaker. Now add a second speaker playing the exact same sound. If the peaks of the first sound wave line up with the peaks of the second sound wave, the overall sound gets louder. If the peaks of the first wave line up with the valleys of the second sound wave, they cancel each other out.
Noise cancelling headphones have a microphone to “hear” the sound around you. They take what they “hear” and produce a sound that’s the same, but shifted, so the peaks line up with the valleys. This cancels out the sound around you.
Many people with normal headphones will crank them really loud to drown out the noise around them. This can damage your hearing. With noise-cancelling headphones, people don’t feel the need to crank them because there’s hardly any outside noise. No cranking means less damage to your ears, so noise-cancelling headphones can actually be beneficial. 🙂
Sound travels in waves like the ocean. Now imagine that you have 2 oceans, with one wave pattern, and another ocean with the exact opposite wave pattern. The two waves will cancel each other out, and leave a calm area of ocean. The same with ANC (Active Noise Cancellation.) A mic is listening to outside noises, and then generating the opposite sound wave to cancel out that noise. If you listen to this it just sounds like white noise(static), but as soon as you listen to it with the outside sounds, they’re much quieter which is why alot of ear buds have the technology to isolate outside noise.
There is no harm in ANC as its the exact same as noise you hear everyday, but opposite. I hope that makes sense.
Noise cancelling headphones do two things. They isolate the noise with the padding around your ears and muffle it a bit. Like what your regular headphones do. The second thing is that they have a microphone built into each side that records the abient noise and inverts the signal in real time. Constant sounds with constant bandwidth disappear ( like jet engine sounds in a plane). Irregular sounds with varrying bandwidth like talking are muffled and almost silenced because irregular sounds are hard to invert quickly.
Sound waves are made up of crest and troughs (loudness and silence). The loudness comes from the air getting pushed and pulled by the speaker. Now imagine what would happen if you could somehow set up another speaker that detects the sound and quickly emits the opposite. So if it detects and loud pushing sound, it’ll emit an equally loud pulling sound. They would cancel each other.
That’s what a noise cancelling system does. It has a sound detector that converts sound into an electrical representation. That electrical signal is fed into an inverter which converts it into the opposite electrical signal. This signal is then fed into a speaker to turn it back into sound. Since it’s the opposite sound to what was detected, they cancel each other out.
This system only works because electricity is far far faster than sound, so the inversion process and the sound emission process are almost instantaneous, so they’re able to cancel the original sound before it travels away.
And no, unless the sounds involved are very loud, noise cancellation shouldn’t damage your ears any more than the original sound might have.
Sounds are moving air. Active cancelation uses a microphone to listen to the sound, and then make an “opposite” sound by pushing air in the other direction. These opposite sounds are added to the music coming through the headphones.
By the time it gets to your ear, the combined air from the original (ambient) sound and the opposite sound created by the device cancel out (mostly), so you hear more of your music with less outside noise.
The music quality is a bit less because the music has extra sound added on top, but there’s no more danger to your ears than listening to regular music.
There is another way to dampen sound, usually used for loud environments like shooting ranges or industrial environments. The earmuffs you wear are actually passive, meaning that even without the system turned on, they are like normal earmuffs with a high noise reduction rating. However they use microphones to transmit sound to your ear but they limit the maximum amount of sound they allow. So at a shooting range, you can talk normally to people but when a gun shot goes off the sound is either cut off, or the sound is allowed through, but at safe volume.
It’s like watching TV where they just turn the volume down on really loud harmful noises.
Active noise cancellation works better on annoying constant white noise, like airplane engine noise.
Sound is a push and pull of the air around your eardrums. Active noice cancellation listens, and pushes while ambient sound pulls, and it pulls when the ambient sound pushes, thus cancelling out. It’s not damaging to your ears, because it’s literally stopping sound from moving your eardrums, same as if you were in a quiet room
Not harmful.
Imagine a sound wave. Imagine another sound wave with the same frequency, but it’s flipped upside down so that the peaks on the original sound wave are at the bottom of the other one when overlayed. The two waves cancel each other out, which would be outside noise in a real life situation
I kind of get why it can’t be implemented in industrial workplaces with heavy machinery, but why is that this will never be possible?
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