noun
closed-back headphones
Headphones with sealed earcups that block outside noise and prevent sound leakage. Often contrasted with 開放型ヘッドホン (open-back headphones).
See also: 開放型ヘッドホン
密閉型ヘッドホンは音漏れが少ないので、電車の中でも使いやすい。
Closed-back headphones have little sound leakage, so they are easy to use even on the train.
Compound of 密閉 (sealed) + 型 (type) + ヘッドホン (headphones). A straightforward technical term.