Noise-Cancellation or Sound-Isolation: What’s the Difference?
Noise-cancelling headphones have become popular in consumer markets over the past few years. This has caused a little bit of confusion about the differences between sound-isolation and noise-cancellation. They're not interchangeable. In this post, we turned to Shure Manager of Technical and Educational Communications Chris Lyons to explain how each type works and what you can expect.
Noise Cancellation
Noise cancellation is an electronic process. It was originally developed to improve radio communications in noisy environments like aircraft cockpits. There's a microphone built into each cup of the headphones that samples the ambient noise near the ear. That noise signal is fed into an electronic circuit that analyzes it and creates a mirror image of the noise, then adds the noise back into the music signal. Some of the real noise is cancelled out by the mirror image inverse noise.
It works best on steady low frequency noise below a thousand hertz or so, for example, the drone of aircraft engines. It doesn't work as well at removing speech or other rapidly changing sounds. Because this is an electronic process, noise cancellation circuitry requires a battery to function. And like all circuitry, it has some degree of hiss and even some digital processing artifacts. Some people complain that when they're wearing noise-cancelling headphones they hear a whooshing or a rushing sound - or detect varying air pressure in their ears.
Which Shure headphones are noise-cancelling?
The answer is none. Shure doesn't manufacture any noise-cancelling headphones.
Sound Isolation
Sound isolation earphones work passively, the same way that earplugs do. The soft pliable sleeves that Shure supplies with its earphones fit snugly into your ears and physically block the outside noise from entering the ear. Just like earplugs, the fit is very important and that's why Shure supplies multiple sizes and multiple styles of sleeves with all of their earphones so you can experiment to make sure that your earphones are fitting perfectly into your ear.
Sound isolation actually provides greater noise reduction than noise cancellation circuitry does. In fact, a couple of years ago researchers at Virginia Tech concluded that Shure earphones performed significantly better than other brands when they were measured head to head. Sound isolation works across the entire audible spectrum, not just low frequencies and not just slow, droning kinds of noise. Sound isolation is great for blocking speech, a noisy television, music – it works in all kinds of environments whether you're sitting on a plane, a train or walking down the street. And no electronics means that there are no batteries, no added hiss, no digital artifacts – nothing except the music, the movie or the game itself.
Which Shure earphones are sound isolating?
The answer is: all of them.
Listen, listen
Everybody wonders whether you can really hear the difference between the earbuds that came with your MP3 player, sound-isolating earphone and noise-cancelling headphones. The answer is 'Yes!' Click on the audio links below to see what differences you can detect.
In an airplane
Here's a sample recording what you might hear in an airplane using the earphones that came with your standard MP3 player:
This is what you'd hear if you were wearing a pair of noise-cancelling headphones:
This is what you'd hear if you were wearing a pair of sound-isolating earphones in the same environment:
On the street
Here's a sample recording what you might hear on the street using the earphones that came with your standard MP3 player:
This is what you'd hear if you were wearing a pair of noise-cancelling headphones:
This is what you'd hear if you were wearing a pair of sound-isolating earphones in the same environment:
On a train
Here's a sample recording what you might hear on a train using the earphones that came with your standard MP3 player:
This is what you'd hear if you were wearing a pair of noise-cancelling headphones:
This is what you'd hear if you were wearing a pair of sound-isolating earphones in the same environment:
Assuming that the earphone are fit properly, which admittedly tends to take a little bit of experimentation, we think that sound isolation does a better job of eliminating the background noise in a noisy environment so that all you have to do is pay attention to the music, the movie or whatever you're listening to on your music player, computer or tablet.
Creating a seal between your ear and ambient noise is part of the magic of sound-isolating earphones. Shure offers a variety of sleeves with its earphones to assure the listener of a perfect fit.
Experts and audiophiles like blogger Salman Ashraft tend to agree. Here's what he had to say in a recent post:
"Sound-isolating headphones simply work better in my opinion. Since sound is never introduced to the ear in the first place (because of the seal), you don't have to fight sound with sound. It's akin to solving a problem before it happens. With noise cancelling headphones / earphones, the external noise already gets into your ear and music while it is simultaneously alleviated with opposing frequencies. Sound Isolating gets the vote from me in preserving good audio quality."
Other considerations
There are two other factors to consider in making a choice: convenience and cost. It may be a challenge to keep the cords from tangling, but it's a lot easier to carry a pair of earbuds in your pocket or backpack than it is to tote a big pair of headphones around. Plus they're inconspicuous and they don't require batteries.
Since sound-isolating earphones lack the additional electronics needed to cancel noise, they tend to be much less expensive. All Shure earphones are sound-isolating and are available in a wide range of prices – starting at $99. Compare that to entry level noise-cancelling headphones three times the price.
Like most decisions audio, making the best choice is just a matter of your personal preferences. Check out the reviews, borrow a pair of headphones from a friend or associate and decide for yourself.
