Dharmaguptaka-vinaya 15.75

15.75

屏處者，見屏處、聞屏處。見屏處者，若塵霧黑闇不見面。聞屏處者，常語不聞聲。

‘Concealed place’ means a place concealed from sight or a place concealed from hearing. ‘A place concealed from sight’ means where, because of dust, mist, or darkness, one cannot see the face. ‘A place concealed from hearing’ means where ordinary speech cannot be heard.