Closed-back

Closed-back earphones with active noise canceling by manufacturers like Bose and Phiaton produce a nullifying frequency to block intrusive sounds.

Source: wiktionary

For a closed-back headphone, they've got a relatively open soundscape, too, which makes extended listening less tiring than some more direct cans.

Source: wiktionary

Luxury French headphone manufacturer Focal has announced that it's launching its first high-end, closed-back pair of headphones aimed at the portable music player market and high-end smartphones.

Source: wiktionary