Headphones 101: Sound isolating vs. Noise cancelling

A good pair of headphones means the difference between serenely listening to your iPod and having to deal with a crying baby on an airplane. Within the last few years, two technologies have come down in price to the consumer level that can help listeners hear only the sounds they like, without any of that extra noise. One technology takes the electronics route, while the other takes an old school approach to isolating acoustics. Which is right for you? Read on as we break down the differences between sound isolating and noise cancelling headphones.

Noise cancelling headphones

All the buzz (pun, anyone?) in the headphone world has been targeted toward noise cancelling headphones. Rather than simply playing back the sound that's sent through the cord, these headphones add in some extra tech to actively block out, or more specifically cancel, any noise coming from outside the headphone.

To understand the tech, lets do a quick breakdown of how a sound is made. Typically, sounds can be thought of as waves. These waves are differences in pressure that your ear can interpret. Our normal sound wave looks like the one we've illustrated below.

If that wave were to be a straight line, no sound would be created. To turn that wave of sound into a straight line, noise canceling headphones send an inverse wave, represented in red below.

The inverse wave combines with the external noise wave, which effectively cancels the unwanted noise.

It might seem strange, but noise cancelling headphones are actually actively transmitting the inverse wave of the external noise in an effort to reduce the overall noise sound. Noise canceling headphones actively do this through a tiny microphone typically embedded in the headphone itself. Since the microphone is listening to the perceived noise, the effect isn't always perfect, but it does a pretty effective job at reducing the noise.

Many different brands sell noise cancelling headphones, though the technology usually comes at a pretty steep premium. Bose, one of the original and best known noise cancelling tech manufacturers, sells over-the-ear and on-top-of-the-ear designs for about $299 for the QuietComfort2 headphones, and $349 for the QuietComfort3 model.

The biggest downside, other than the prohibitive price, is that the headphones are actively cancelling audio, meaning if the battery dies, so does the user's music. For that price, we'd think Bose might have a passthrough mechanism that would let users keep listening even when the battery is spent.

Sound isolating headphones

For some headphones that take a different, more traditional tact — and will work without a battery — check out sound isolating headphones. These earbud-style headphones don't need a lengthy explanation or graphs, as they work in a pretty easy to understand manner.

Sound isolating headphones create a seal with the ear canal, like earplugs, which prevents any external sound from ruining the vibe. Sound isolating headphones are very different from the standard earphones which come with an iPod or other portable media player. Sound isolating earphones typically have a bit of a spongy membrane which helps them fit comfortably in the wearer's ears.

Unfortunately, the most common complaint with sound isolating headphones is comfort; more specifically, lack thereof. While the effect of sound isolating headphones is unmatched, finding the right size cone takes a bit of trial and error. Too small of a tip, and the earbuds won't isolate the sound nor stay in the wearer's ear. Too large, and the same is true except the buds are even more uncomfortable. Shure's latest brand of headphones, the E-series, comes with a variety of interchangeable tips to combat wearer discomfort, as do many other sound isolating earbuds.

The biggest boon of sound isolating headphones is the variety of price ranges. Since the effectiveness of the noise isolation doesn't depend on electronics, less expensive headphones can do an effective job at keeping the noise out. However, there's an entire spectrum of sound quality that's coupled with the wide variety of sound isolating headphones. Expect to spend $50 for the low-end, and on the high-end users spend up to $600 for a set of 'buds. I'm happy with my Shure E110 headphones, which cost about $100. I've personally found the headphones to be a godsend. While using them on a plane, I'm able to block out any crying baby or other inconvenience and focus solely on in-flight TV or the best of my iPod.

Which is better?

While I can't pick one definitively over the other for everyone, I will say that I definitely prefer the sound isolating earbuds to the traditional noise canceling cans. Without mentioning convenience (I'd rather stuff earbuds in my pocket than cart around gigantic over-ear headphones) I prefer sound isolation to noise canceling for a few reasons. For one, it doesn't take extra batteries or drain extra battery power to get rid of unwanted noise. Secondly, the price of a good pair of sound isolating headphones tends to be cheaper than a comparable pair of noise canceling headphones. And third, some have argued that sound isolating headphones can be better for your hearing since the user can achieve a higher level of sound at a lower volume, since there's no external sound. Noise canceling headphones still put pressure toward the ears, though the pressure is inaudible. For those three reasons, I lean on the side of isolating earbuds.

What about you? Do earbuds give you the heeby jeebies? Or would you prefer a pair of earbuds to gigantic headphones any day? Sound off in the comments and let us know which headphones you like, and whether you prefer sound isolating or noise canceling.

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