The heavenly choirs were directing their praises to God who sat upon the throne. But now there are other sounds that require God’s attention, namely, the petitions of the saints (be they under the altar, be they on earth). Of course it is not so that God Almighty is not able to hear the choirs and the saints at the same time. Rather, with this silence the Holy Spirit communicates that the Lord God gives his full attention to the cries of the saints.
4 La fumée des parfums monta, avec les prières des saints, de la main de l'ange devant Dieu.