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!