What’s Actually Happening in Your Noise-Canceling Headphones
41 Comments


Are the sounds of throat clearing, construction,
or the clack-clack-clack of computer keyboards making you scream inside? Before you commit a serious crime, let’s
talk about some OTHER solutions, like noise-canceling headphones. And specifically, how do they work to drown
all those terrible noises? The first patent for noise cancellation showed
up as early as the 1930’s, though, it wasn’t until 1986 when the technology made its big
debut when two pilots took flight in the Voyager aircraft for a non-stop trip around the world,. The ultra-lightweight cockpit design wasn’t
insulated and sat directly above the engine, which needless to say, was very loud. Bose provided a prototype device to dampen
the sound. Soon after, the aviation industry, the military,
and eventually consumers began to adopt noise cancellation technology. To understand how this tech works, we need
a little primer on the physics of sound. Sound waves, or pressure waves, are essentially
just the mechanical vibrations of particles moving through a medium—like air—which
can consist of varying densities. As the particles react to these waves, they
compress air together, and then expand back out again, producing a series of peaks and
troughs. Depending on the density of the medium that
they’re traveling through, the distance between each point of high and low pressure
can vary, which is what we call amplitude. The amount of time between each period of
compression and expansion is what’s known as frequency, otherwise known as pitch. Most noise-canceling makes use of two technologies,
and the first is pretty low tech. Known as “passive noise cancellation,”
it’s about as complicated as putting your hands over your ears to create a tight seal. Headphones can be molded into specific shapes
and include sound-absorbing materials, like high-density foam or earbuds, that partially
block sound waves. Something as simple as an earbud that fits
snugly into your ear canal is another example of the tech that’s often marketed as “noise
isolating”’ Getting a good seal can be a challenge, however—since
everyone’s ears are different and not all headphones fit equally well.,
The second technology is active noise canceling. Microphones built into the headphones detect
ambient sounds and convert them into an electrical signal. The new sound wave is flipped, and is known
as an antiphase,,. When the two waves combine near the listener’s
ear, the opposing sound waves cancel each other out. Known as destructive interference,, the result
is near silence, allowing you to immerse yourself in a favorite tune or just hear yourself think! But this technology is not perfect. That’s because the microphone and antiphase-producing
speakers aren’t exactly in the same location. The antiphase isn’t a perfect inversion
of the actual sound. So instead of hearing no airplane engine, you hear muffled airplane
engine. Devices with built-in microphones located
close to the ear means headphones only have microseconds to calculate an antiphase signal
and send the ambient sound to your ears. It works well for low-frequency sounds, but
noise-canceling headphones struggle with shorter, high-frequency sound waves. So if you’re looking to shut out noise like
human voices, dogs barking and babies crying, you’re going to need that passive noise
cancellation too. However, some active noise-canceling headphones
can have a noticeable distinct hiss. This hiss is called the “noise floor,”
and it’s actually made by the electronic circuitry itself. A lack of uniformity in the copper wire, sensors,
and soldering cause electrons to stutter or bounce, producing noise that’s present in
all electronic devices from cell phones to amplifiers. Depending on the quality of the headphones,
newer models are able to minimize this unwanted sound, which is often reflected in their price. In the future, you might not have to put on
bulky headphones or shove a device in your ear to experience the benefits of active noise
cancellation. Its appeared in cars that use accelerometers
in combination with microphones to measure the vibration of sounds coming from uneven
pavement, reducing the noise that passengers hear., For more stationary environments, engineers
at the University of Illinois are researching how to take advantage of the fact that wireless
signals travel a million times faster than sound. By placing microphones closer to a noise source,
like chatty coworkers, a more accurate cancellation signal can be transmitted to an ear device
faster than the speed of sound—all before the sound even arrives at the listener. Noise cancellation technology has come a long
way since the Voyager flight, and it looks like we can expect to see some exciting developments
in the near future…but if you’re planning on wearing your noise-canceling headphones,
you might want to take them off every once in a while, or you won’t hear the news. Fun fact: Speaking of sound, the term misophonia
literally means “hatred of sound”. It’s a condition where negative emotions,
thoughts, or physical response is triggered by specific sounds. So tell us, what sounds
do you find absolutely intolerable? Let us know down in the comments and don’t
forget to subscribe to Seeker. Thanks for watching!

41 thoughts on “What’s Actually Happening in Your Noise-Canceling Headphones

  1. Damn, I just wore them. I is quite fascinating to know how these work and preventing me from getting insane. Thanks to Seeker!!

  2. Wonder how vibration and wave length Affects chemical Reactions. . How does chemical Reactions even cause feelings.
    What are feelings any way. Scientifictically.

  3. New apps Google "Sound Amplifier" is Accurate to equalize noise. download it and its for free..Take a look at "Sound Amplifier"
    https://play.google.com/store/apps/details?id=com.google.android.accessibility.soundamplifier

  4. So then does that mean you lose your hearing twice as fast then?
    If its broadcasting the opposite sound as well as the actual sound????

  5. Misophonia? Well, I have a definite antipathy towards any kind of knocking or bumping noise, especially if I'm not expecting the noise. It makes my heart speed up and then immediately I deep breathe to put my heart to rights again…sometimes it takes a while, longer than 15 seconds, to feel okay again…

  6. Yes by all means, lets put microphones throughout the office and especially near chatty co workers while trying to ignore them with head phones. lets take a guess who will be working there last. talking about a no bully work environment.

  7. Even with my hearing protection on at work, I can still hear the agitator (I think) in the spray booth when the finisher is changing colours and trying to clear the line. This inconsistent tik-tok as he adds thinner and sprays it through and then stops and checks and starts again drives me crazy. Maybe it's because my (passive) hearing protection filters out noisier sounds that I can hear this so clearly or just because it's inconsistent, I don't know but I've never heard anyone else complain about it.

  8. The tick-tock sound of a wallmounted clock in a silent room. That watingroom boredom is something todays kids with phones cannot imagine. That sound almost triggers a minor depression!

  9. @seeker I just want to say i love the polls u guys conduct and then teaching us about it etc. it feels very interactive. 😀

  10. The noise cancelling effort can mess up your inner ear and cause you to suffer from nausea and vomiting. Temporarily of course, but enough to ruin your day.

  11. Great video!! Loved your explanation. One lil' correction that i'd give ya; at 1:20 the amount of TIME it's actually known as PERIOD not frecuency.

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