The General Instruction of the Roman Missal, 2011 states: "In Lent the playing of the organ and musical instruments is allowed only in order to support the singing. Exceptions, however, are Laetare Sunday (Fourth Sunday of Lent), Solemnities, and Feasts." This instruction helps us, the faithful, to better enter into the subdued and penitential nature of this season.
For more information, see the articles below.
"6 Liturgical No-No's During Lent"