Is it permissible to pray silently for the prayers that are recited aloud, especially Fajr and Isha prayers, to avoid disturbing a Christian roommate?

For an individual praying alone, it is sunnah to recite aloud in congregational prayers according to the Maliki and Shafi'i schools, and one narration within the Hanbali school. According to the Hanafis and the relied-upon opinion among the Hanbalis, one has the choice between reciting aloud or silently. Your prayer is valid even if you intentionally recite silently in prayers where audible recitation is legislated. It is obligatory to strive to perform prayers in congregation, either in the mosque or in the university's prayer room if available; otherwise, in the university square or in homes. Non-Muslims should be invited to Islam.