The low-tech, or passive, way to cancel noise is simply to wear closed-back, circumaural (around the ear) headphones or very snug in-ear canalphones. These shield your ears by sealing them off from the outside world. Because of their impressive aural isolation abilities--equal to or better than those of battery-powered noise-canceling models--you won't have to crank up the volume to overcome background noise when using these 'phones. Passive isolation earbuds are also much lighter than their active noise-canceling counterparts but you pay extra for the compact coolness and stellar sound quality.

Est. price: S$499 (US$299)

1. Etymotic ER-4P MicroPro Earphones   CNET Rating: 9 out of 10 The good:  State-of-the-art in-ear headphones; extremely effective noise isolation; reference-quality sound; gold-plated miniplug; storage pouch. The bad:  Extremely expensive. The bottom line: Etymotic's ER-4P MicroPro earbuds cost a king's ransom but offer royal sound quality. Read review

Est. price: S$245 (US$120)

2. Etymotic ER-6 Isolator  CNET Rating: 8 out of 10 The good:  Noise-isolating earbuds with awesome clarity and detail; gold-plated miniplug; travel pouch included. The bad:  Tangle-prone wires. The bottom line: Etymotic's affordable high-end earbuds have a big sound. Read review

Est. price: S$299 (US$179)

3. Shure E3c  CNET Rating: 8 out of 10 The good:  Pro-style earbud headphones; effective seals provide ambient-noise isolation; excellent sound quality; storage pouch; 30-day money-back guarantee; two-year warranty. The bad:  Not for fans of bass-heavy music; uncomfortable for some. The bottom line: The E3c is expensive, but if you're into the stealthy form factor of earbuds, you'll be hard-pressed to find a better-sounding pair. Read review

Est. price: S$169 (US$99)

4. Shure E2c  CNET Rating: 8 out of 10 The good:  Excellent sound quality; effective ear seals provide ambient-noise isolation; storage case; 30-day money-back guarantee; two-year warranty. The bad:  Wires have a tendency to tangle; tricky to place in ears. The bottom line: These small, cone-shaped earbuds offer excellent isolation and pro sound quality. Read review

Etymotic ER-4P MicroPro Earphones (Click to view larger pic)

Etymotic ER-4P MicroPro Earphones
What to expect:
The name Etymotic means "true to the ear" and is pronounced "et-im-oh-tik." Established in 1983, the company's initial mission was to design products to measure, improve, and protect hearing. The Etymotic ER-4P headphones were designed for use with portable CD and MP3 players and retail for a whopping S$499 (US$299).

Yes, they're expensive, but if you've already shelled out big bucks for an iPod, the ER-4P will deliver your MP3 player's full sound potential. The Etymotic headphones employ advanced technology originally developed for hearing aids. Another reason for the high price: ER-4P headphones are hand-built by a skilled technician working with stereo microscope, then measured and tested at Etymotic's factory in Elk Grove Village, Illinois. (Etymotic also makes the ER-4S and the ER-4B, which are not designed for portable use.)

Like the other in-ear headphones we recently tested, Shure's E3c, you have to cram the ER-4P's eartips deep into your ear canals, which might be a deal breaker for some buyers. (Also, the rubber eartips in particular have a tendency to attract ear wax and must be cleaned regularly.) Rest assured, Etymotic Research is dedicated to hearing protection, and the ER-4P 'phones are very safe. In fact, because of their impressive noise-isolation abilities, equal to or better than those of battery-powered noise-canceling models, you won't have to crank up the volume to overcome background noise. The Etymotic ER-4P is the ultimate travel aid for frequent flyers or train commuters, and we found these headphones more comfortable than the Shure E3c, though those with smaller ear canals may prefer the latter.

With some earbuds, it can be hard to distinguish between the right and left bud, but the ER-4P keeps things simple: the earpieces are color coded--red for right and blue for left. The ER-4P has a 5-foot cord that ends with a 1/8-inch stereo miniplug, along with a 1/4-inch adapter plug. You can use the provided shirt clip to tack the dangling headphone wire to your shirt or jacket. Filling out the package is a travel pouch and a larger home storage box, along with three pairs of interchangeable rubber eartips and five pairs of foam ones.

Sound quality is astonishingly good; it's hyperdetailed but never harsh or irritating. You can even hear reverberation and the acoustics of the studio where the musicians recorded the music. Bass response, never a strong suit for earbuds, is nicely balanced and deeper than average. No, it's not as warm as that from the full-size Grado SR60 headphones, but the overall quality of the ER-4P leaves the Grado and every other portable headphone set we've ever tested for CNET in the dust.

The Etymotic Research ER-4P is a true reference-quality design and is highly recommended. But because of the exorbitantly high price tag, we're giving the Editors' Choice nod to the ER-4P's step-down sibling, the Etymotic ER-6 Isolator. At just S$245 (US$130)--and cheaper online--it offers much of the ER-4P's performance and features at a significantly more affordable price.

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Etymotic ER-6 Isolator (Click to view larger pic)

Etymotic ER-6 Isolator
What to expect:
The name Etymotic means "true to the ear" and is pronounced "et-im-oh-tik." We're huge fans of the company's ER-4P headphone set, but it retails for a whopping S$499 (US$299); the ER-6 Isolator, meanwhile, carries a list price of S$245 (US$130) and is designed to offer most of the performance and features of its pricier sibling for a lot less money.

The ER-6 comes with both silicone rubber and foam eartips, which the user can swap. They're designed to fit into your ear canals, like earplugs, to block out ambient noise. We judged their effectiveness to be the equal of active or battery-powered noise-canceling headphones. There's just one caveat: some buyers, particularly those with smaller ear canals, may find the eartip insertion rituals a bit daunting or unpleasant (you really have to jam them in). Also, the rubber eartips in particular have a tendency to attract earwax and will have to be cleaned regularly. But this reviewer found the ER-6 to be highly comfortable--arguably more so than other top in-ear headphones, including the Shure E3c or the Etymotic ER-4P. On the other hand, some CNET editors preferred the fit of Shure's E3c.

As with those in-ear models, when we walked or moved, we heard the ER-6's wires rubbing against our clothing. You get used to the sounds over time, but they're there, and the ER-6's very thin and superflexible wires are prone to tangle; ours did, even after we carefully stowed the headphones in their carry pouch.

Ah, but the ER-6's sound is extraordinarily fine. Because of its noise-isolation attributes, on a roaring NYC subway train, we were able to listen to our iPod at very moderate volume levels; we didn't have to blast our ears to enjoy our music. Then again, if you want to play loud, the ER-6 can achieve fairly high levels with a portable MP3 player, though the ER-4P was able to play louder.

Listen, and you'll hear a purity to the sound that few 'phones can match; we were constantly surprised by the ER-6's ability to resolve even the most subtle details of our music collection. Bass response is excellent--deep and well defined--for an earbud-type headphone. Bass buffs will be happier with a full-size Grado SR60, our iPod headphone champs. However, overall the ER-6's sonics are cleaner and far more resolved than the SR60's. As always, your buying decision is a matter of identifying your priorities.

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Shure E3c (Click to view larger pic)

Shure E3c
What to expect:
The Shure E3c earbuds are the descendants of the company's in-ear monitors for onstage musicians. Wyclef Jean, Wilco, Jethro Tull, Everclear, Nikka Costa, Tricky, Herbie Hancock, and Oasis all use Shure products. Now, thanks to a bit of trickle-down technology, a range of Shure in-ear models is available to consumers. Listed at S$299 (US$179), the E3c is in the middle of the group.

The tiny E3c weighs less than an ounce; it comes with a sturdy storage pouch. The earpieces are white, complementing Apple's iPod.

The E3c achieves its full bass response only when you push the buds pretty far into your ear canals. To ensure the best possible fit for ears of all sizes and shapes, Shure includes both reusable flex sleeves and disposable foam sleeves in small, medium, and large. Compared with the flex sleeves of the S$169 (US$99) step-down E2c, the E3c's fit more snugly, so we found them more comfortable, but not everybody will like them. However, you'll have some time to test how the headphones feel in your ears before you make a final commitment. The E3c comes with a 30-day money-back guarantee and, for the long run, a two-year warranty.

The E3c blocks high levels of ambient noise in planes, trains, buses, and any other environment, so you can hear all of your music's detail without cranking up the volume and blasting your ears. The E3c isn't an active noise-canceling model, but in our comparison tests, it shut out noise just as well, and better yet, its hushing abilities don't rely on batteries.

The E3c's sound is nice and warm, with incredible clarity and transparency. Even when you're listening at low levels, the headphones effortlessly bring you the fine detail in your music. And if you want to turn up the volume, the highly efficient E3c will play as loudly as any headset driven by a portable device's meager watt output. Shure designed the E3c to be accurate, and it is, so don't expect it to blow you away with hyped-up bass or sizzling high frequencies. If you crave heavyweight bass, move up to a full-size, over-the-ear model.

When we compared the E3c with the E2c, the family resemblance was obvious, and each offered equal isolation from external noise. But the sound of the less expensive model struck us as thinner and not as clear. The E3c's richer and more palpably realistic audio clinched the deal for us.

More important is the way the E3c always brought us closer to the music. Playing CDs we've listened to countless times, we were constantly finding new details and gaining further insight into the songs. The E3c is an audiophile delight.

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Shure E2c (Click to view larger pic)

Shure E2c
What to expect:
The Shure E2c is a result of the company's experience designing in-ear monitors for onstage musicians. Wyclef Jean, Wilco, Jethro Tull, Everclear, Nikka Costa, Tricky, Herbie Hancock, and Oasis all use Shure products. Thanks to a bit of trickle-down technology, Shure is now offering a range of consumer in-ear models, of which the S$169 (US$99) E2c is the most affordable. It features a 62-inch copper cable and an adjustment tube that secures the wire comfortably behind your head. You also get a storage case with a cable spool.

To get any bass out of the E2c, you need to push the earpieces pretty far into your ear canals. Since human ears vary in size, Shure provides small, medium, and large pairs of disposable foam sleeves and reusable flex sleeves to ensure the best possible fit.

Now that those provisos are out of the way, let’s get to the E2c’s strengths. While these are not noise-canceling headphones, they block out ambient noise almost as well. We wore them on the New York City subway in our brute-force noise-cancellation test, and we came away quite impressed with the E2c’s quieting effect. We didn't have to turn up our iPod's volume to overcome the high background-noise levels.

The E2c delivers a cleaner aural experience than most earbud models, so you hear greater detail without suffering excessive brightness or harshness. Bass definition and power are quite good. In fact, the E2c's sound quality compares favorably with that of our reference full-size headphones, Grado's SR60.

While the deep-mounted earpieces may take some getting used to, the E2c sounds great. And since it's sold with a 30-day money-back guarantee, you can audition its comfort and audio quality for yourself risk-free.

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