On various feasts throughout the year, the Church has a tradition to recite or sing a special "sequence." On Pentecost, the sequence is entitled Veni, Sancte Spiritus and invokes the Holy Spirit, asking for the Spirit to come and refresh our weary hearts.
The sequence dates back to at least the 13th century and has been used in the liturgy on the feast of Pentecost ever since.
While often these hymns can go by quickly during the liturgy, in truth these are prayers and can be prayed privately as well, opening our hearts to the dwelling of the Spirit.