Hitachi Maxell today unveiled noise-canceling iPod-only earphones [JP] that are powered through the player and therefore don’t require extra batteries. They weigh 22 grams and are 95cm long.

All that users need to do is to plug the HP-NC20.IPs to the dock connector, having to take into account the battery life will be reduced by up to a whopping 66%. In addition, users are forced to control the volume with the slider on the earphones since volume control on the iPod itself won’t work anymore.

Hitachi Maxell promises a maximum of 20dB of less noise. The earphones are only compatible to fourth generation (and up) iPods and iPod Touches of the first and second generation (they don’t connect to iPhones).

The HP-NC20.IPs will only be available in Japan for the time being (from December 12) and cost $80.