The term “Gospel Acclamation” seems to be causing some confusion, with some thinking it is the Gospel being proclaimed. The terms used in the Roman Missal are:
“The Acclamation before the Gospel” (the heading for General Instruction of the Roman Missal, n. 62) or
“Verse before the Gospel” (used in GIRM 63) or
“the Alleluia Chant before the Gospel” (used in GIRM 43).
Often it will be clear when to stand, with the Alleluia being sung and enough of the ministers and congregation knowing what to do. But there may be confusion and the requirement of an announcement or gesture.
Some examples of situations where there may be confusion are:
– There is the option to have only the Gospel reading, following Directory for Masses with Children, n. 42. So the Acclamation before the Gospel is directly after the Collect.
– Some Masses have a Sequence, sung before the Alleluia (GIRM 64). I do not think it is clear in the Roman Missal if the congregation should be standing or sitting for this. A decision needs to be made and perhaps communicated.
– At a Mass where there is only one reading before the Gospel “the Alleluia or the Verse before the Gospel, if not sung, may be omitted.” So if it is omitted, what is the cue for people to stand? Particularly if there is silence after the second reading, which may be appropriate according to GIRM 56.
GIRM 43 has: “For the sake of uniformity in gestures and bodily postures during one and the same celebration, the faithful should follow the instructions which the Deacon, a lay minister, or the Priest gives, according to what is laid down in the Missal.”
I think saying “please stand” would usually be enough.