The Preface is sung or said by the principal priest celebrant alone; but the Sanctus is sung or recited by all the concelebrants, together with the congregation and the choir.
After the Sanctus, the priest concelebrants continue the Eucharistic Prayer in the way described below. Unless otherwise indicated, only the principal celebrant makes the gestures.
The parts spoken by all the concelebrants together and especially the words of consecration, which all are bound to say, are to be said in such a way that the concelebrants speak them in a very low voice and that the principal celebrant’s voice be clearly heard. In this way the words can be better understood by the people. It is a praiseworthy practice for the parts that are to be said by all the concelebrants together and for which musical notation is provided in the Missal to be sung.