Hitachi Maxell iPod-Only Noise-Canceling Headphones Don't Need Batteries These noise -cancelling headphones from Hitachi Maxell are unlike many previous similar types since they don't require separate power. Instead they connect to iPods via the dock connector, and can suck on the batteries through there. They do manage about 20dB of noise canceling with an "Active Noise Rejection" system, but the design is curiously crippling: they can only connect to iPods (4th gen or later) and iPod touches—not the iPhone. And to draw power this way means you'll get reduced iPod battery life, which may be as much as 50%. And the iPod's volume control doesn't work, so you have to use the slider on the headphones. Weird, but these HP-NC20.IPs are only about $80 in Japan, so you may still be tempted. [AVWatch ]