Father Peter Schineller, an American Jesuit who has authored a "Handbook on Church Music -- for Choirs, Priest and Catholic Faithful," offers this commentary on the primacy of the priestly role in fostering the participation of the congregation in the chants of the Mass.
It makes sense to me that, if the dialogue between the priest and the faithful is given added solemnity through the use of chant, then the congregation will more readily participate in the other chants and hymns as well.
"Father Schineller correctly places much of the onus on the priest to carry out the Church's desire regarding the proper order of liturgical singing. The traditional simple chants used for singing priestly prayers and greetings are well within the range of most priests although the magnificent tone for the preface can sometimes be a challenge.
The priest is the first who has to lose his fear of singing, including his fear of appearing ridiculous. Once begun he will find that singing the prayers and greetings not only adds a touch of solemnity but also frees him from the temptation of having to act or stress the prayers in order to put feeling or meaning into them.
Thus singing, rather than emphasizing the individual personality of the priest, serves to accentuate his priestly function.
These prayers were probably composed in order to be sung and find their best expression in the traditional simple prayer chants or in similar tones adapted to the vernacular.
Once the priest leads he will find that the people will follow him. And the spiritual benefits of singing the Mass will undoubtedly follow for, as St. Augustine said, 'He who sings prays twice.' "
I don't know why Father Schineller says "probably" with respect to the manner in which the prayers of the Mass were intended to be recited. From the earliest days of the Church, the Mass has always been sung. See here for some background information on chant in the early Church.
This is so true.