Sacrosanctum Concilium 120 says:
“But other instruments also may be admitted for use in divine worship, with the knowledge and consent of the competent territorial authority, as laid down in Art. 22, 52, 37, and 40. This may be done, however, only on condition that the instruments are suitable, or can be made suitable, for sacred use, accord with the dignity of the temple, and truly contribute to the edification of the faithful.”
Does this mean that something like an electric guitar or modern drum kit could be used? Could these instruments be considered suitable for ‘sacred use and in accord with the dignity of the temple’? Would a priest need permission from his bishop to allow such instruments at Mass? Could the local bishop allow any instrument to be used?
Are only hymns from the approved hymnal allowable at Mass?
I’m not asking for people’s opinions about what is and what is not appropriate, I’m asking if anyone knows the definitive rules on this.