If short, intense sessions with your iPod are your bag, these new Maxell heaphones might just do the trick. Compatible with your fourth-gen iPod (or your first and second-gen iPod touch) the HP-NC20.IP earbuds offer active noise cancellation from 50-700Hz and noise suppression up to 20dB. Since they rely on the iPod dock for audio and power, you're stuck using the volume control on the headphones themselves, and battery life is significantly reduced -- anywhere from one half to two-thirds. If you're one of those people who never stops rocking, you might want to stick to something a little more passive, headphones-wise. But if you tend to "rock out" in concentrated amounts, these just mig
