A (more or less) complete answer to your question can be had by studying the "General Instruction of the Roman Missal" (the "GIRM"), particularly 39-41 and 46-90 (passim).

More general norms can be found in the 1967 instruction Musicam Sacram, (esp. 16-36), which you can find here.

Credo, for example, is sung antiphonal. The choir sings one part and then the congregation sings the next part and so on. That's how I understand it. Then how do we know what part the congregation should sing?

The exit hymn? Shouldn't the Liturgy end with the Marian antiphon?

Henrik: the credo may be sung antiphonially. Also, the Marian antiphon, while a laudable tradition, is not required (or even found in church documents as a recommended usage, if I recall).

And, as I keep pointing out: if you sing it, you cannot also omit it.

[-1 for obfuscation.--admin]

Oh, for crying out loud. Either it is omitted or it is not, and if it is not omitted it may be sung or it may be spoken. End of story.

The above comment is a joke based on how the wording is put:
"If not sung, it may be omitted."

The obvious implication of this is: If you sing it, you can not also omit it.

Acquit the omit if it does not fit.

There is nothing that "must be sung" at any Mass, Sunday or weekday..

The Gospel Alleluia only to be sung and may not be spoken - so if there is no one to sing it, cut it.

We really need to abandon the idea that there must by music and or singing at Mass. That becomes a starting point for revising the liturgy, not singing the propers.

Get rid of the need for a cantor spewing a responsorial psalm and gospel alleluia and then ban lay people from doing the readings, put the readings back into the mouth of the priest and get rid of him sitting and watching the Mass proceed when he should be leading it.

Priests have handed the liturgy to people who know nothing about it, people who have not given their lives to study and preparation. Altar boys in the 1950's had more commitment to being at Mass than laypeople doing the readings...not to mention the ridiculous "extraordinary ministers of the eucharist". The parish I was at had the bizarre practice of a person standing up front and hold fingers up during the Agnes Dei to indicate how many EMOTE they were short that Mass....if people do not show up when assigned to distribute the Eucharist, it shows how little respect and understanding of the presence of Christ in the eucharist...and this practice must be halted.

It is difficult to admire lay people in the pulpit with their imperfections, the imperfections of all of us.

A priest with human failings is still a person who has given up much to be a priest and as a result, can be admired. A priest who is know to be a drunk rises above that to say a Mass and is respected.

The people need never sing at Mass. They should be silent. If they sing it should be the ordinary parts of the Mass first, 1-5 above. Once they are comfortable doing that then a small choir should sing the propers during the processions.

Then, at the main Sunday Mass, the Alleluia and Psalm should be sung. The people should sing the Alleluia, but not the psalm antiphon. Sung parts of the Mass that change should never be sung by the congregation, for this creates a situation in which there is no true full participation by the people since many will not sing the changing parts.

That's what Vatican II was all about, full participation by all. Anything that people will not do freely HAS to be omitted - and singing of changing parts is definitely one of them.

This may sound like BS, but attend ANY church and listen to the people. They WILL respond with spoken responses. They all will not sing them.

The church has always been practical. The practice of singing the Psalm antiphon is not a practical practice.

[played a silent movie last night. Got a black and white film of the 48 star American flag being raised and waving on the screen, invited the people to stand and sing the national anthem. Every person stood up and sang. Any more questions?]

People will sing things they know due to repetition. Changing the ordinary music a couple of times a year will cause a drop in participation. Changing every week means that most people will not sing and ante not included in the Mass.

I beg to differ, Noel. I know everyone has a different experience, but the congregation at our small EF Missa Cantata sing the Ordinary and the opening and closing hymn, the Marian antiphon and all of the sung responses with great enthusiasm.

Some of them have also begun singing the Communion antiphon which we always sing with a few verses. We sing a different Mass setting every month, and the people do a great job singing along. We have learned close to ten chant Masses settings in four years.

Two things which help a great deal I think: First, we're in a small chapel, and the schola is located with the people in the nave (see part of our schola below preparing for Mass.)



Second, our handout which I think is key in helping the people feel they are welcome to sing along. A number of people have told me just seeing the chant every week has helped demystify it and they are beginning to understand how the notes "go up and down."

WHS.

Is that first initial standing for "What H____S____!?" Hey, just trying to help a fellow ol' hippy bro' out. I shoulda known not to channel my inner Sartre, Kierkegaard, Hawking! Slowly walking backwards out of the room.....

@JulieColl

Have you recorded audio and/or video?

meloCharles, I thought it was "What He Said." I thought Noel was agreeing with you. FWIW.

@AdamWood God bless! So kind of you. If you're ever in NYC hope you visit and we'll all go out on the town and show you Texans how to party. : )

especially when the local bishop creates a Sunday afternoon ghetto existence for EF groups, draining the few people in most parishes that would stand up for authentic liturgies.

This struck home. I agree; going to the EF Mass in a cemetery is about as far away from the mainstream as one can get, but, believe me, we stayed in our own OF parish as long as we could before fleeing for our spiritual lives and sanity.

One of the many reasons I'm so grateful for this forum is the opportunity to stay connected, as much as is possible, with other Catholics, and discovering that there is definitely a consensus among the members as to what constitutes authentic liturgy, even though it may have many different expressions.

Until (and it may never occur, and maybe it isn't necessary and or desirable) there is some sort of official "liturgical reconciliation" between the two forms of the Roman rite, as Pope Benedict sometimes referred to, it's important for people to know that there is already in practice a general liturgical "ballpark" around which Catholic musicians should hover and not stray too far from.

I actually attend both forms of the Roman rite (although a non-Catholic).
My question was actually about Gregorian chant. But please have your nice debate...