開放 かいほう がたヘッドホンではありませんでした
kaihōgata heddohondewārimasendeshita

Noun
Desu Copula

The polite, past negative form of 開放型ヘッドホン

1. Was not an open-back headphone.; Was not an open-type headphone.

Past/Perfective
Negative
Polite
Formal Register