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| Product: Sony MDR-NC20 Headphones |
Company: Sony |
| Web: www.sony.com |
Phone: 201-930-1000 |
| Platform: Your head |
SRP: US$200
Street Price: $130 |
Cred Rating: | Special Award: |
Noise canceling is a very cool concept, and one that's fairly easy to
grasp. Take a sound wave, match it with its exact opposite, and the
two waves cancel each other out, resulting in silence. To illustrate, here are some simple sine waves:
Fig. A: Wave 1, the original sine wave
Fig. B: Wave 2, the opposite of wave 1
Fig. C: Waves 1 and 2, superimposed
Fig. D: Waves 1 and 2, combined
Since wave 2 is the exact opposite of wave 1, the two cancel each
other out. Whenever wave 1 goes up, wave 2 goes down by the exact
same amount, and vice versa. Add wave 1 to wave 2 and the result is 0
(a.k.a. silence).
Noise canceling headphones use a pair of microphones (one on each
earpiece) to capture incoming noise. A microprocessor analyzes the
noise and creates the exact opposite signal. At the same time, this
noise is subtracted from the signal coming from the headphone jack so
that your headphones don't also kill the sound from the They
Might Be Giants CD you're listening to. The end result is, ideally,
the sound of the CD without any of the noise from the loud world
outside your headphones. You hear the music clearly without having to
crank up the volume.
The real world doesn't always cooperate with this scheme. Affordable consumer-grade noise canceling technology works best with low-to-mid-range
frequencies and on regular, droning sounds. Jet noises from inside
the cabin, the sound of an air conditioner motor, a lawnmower --
these are what noise cancellation handles best. Sharp, shrill or
transient sounds like a jackhammer, the metallic squeal of a subway
train taking a curve or firecrackers going off will inevitably foil
noise-canceling headphones.
Along with several other manufacturers, Sony has a line of
noise-canceling 'phones. The MDR-NC20s is their top-of-the-line model. Sleek
and portable, they fold up and stow in a small faux-leather pouch.
A single AAA battery will power them for several dozen hours of
listening, and they can also be used without the noise cancellation if the
battery dies. As regular headphones, they sound pretty good, although
not as good as Grado SR-60s costing less than half as much.
Within limits, the noise canceling works reasonably well (OK on
planes, poorly on the subway). People next to you sound like they're
several feet away. Traffic noise recedes into the background. Every
once in a while, the headphones can't quite keep up with the external
racket and there's an odd, unpleasant throbbing as they struggle to
keep the world at bay.
Sony really blew it with the cord which comes in two parts. The headphones end
in an odd, tiny, nonstandard connector; this fits into a jack on the
last three feet of wire, which finally ends in a standard mini plug of
the type usually found on headphones. This ridiculous design almost
guarantees that at some point the weird connector will malfunction or
you'll lose the 3-foot section of cord you need to actually *use*
the headphones.
On an inexpensive set of 'phones, the flaws of the MDR-NC20s would be
acceptable...but these babies are far from inexpensive. You'd be better
off getting one of Sony's fine closed-ear models that block out some
external noise, have better sound and cost significantly less.
- Andrew Sasaki [3/5/01]
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