Music During Exposition

During the exposition there should be prayers, songs, and readings to direct the attention of the faithful to the worship of Christ the Lord. To encourage a prayerful spirit, there should be readings from Scripture with a brief homily or exhortations to develop a better understanding of the eucharistic mystery. It is also desirable for the people to respond to the word of God by singing and to spend some periods of time in religious silence (Holy Communion and Worship of the Eucharist Outside of Mass, 95)

The Church does not specify in detail which songs may or not be sung during exposition.  The general rule of thumb, however, is that Church liturgy requires liturgical music.  Exposition and adoration are considered liturgies of the Church and therefore require appropriate liturgical music.