In 1963, as a result of the Ecumenical Council Vatican II, Pope Paul VI promulgated the ” Constitution
on the sacred liturgy”. One of the early paragraphs links “proper disposition” to “minds…attuned to.. voices”.

11. But in order that the liturgy may be able to produce its full effects, it is necessary that the faithful come to it with proper dispositions, that their minds should be attuned to their voices, and that they should cooperate with divine grace lest they receive it in vain. Pastors of souls must therefore realize that, when the liturgy is celebrated, something more is required than the mere observation of the laws governing valid and licit celebration; it is their duty also to ensure that the faithful take part fully aware of what they are doing, actively engaged in the rite, and enriched by its effects.

Constitutution on the sacred liturgy (1963)

What does that mean? Should we not think before we speak? Should we not tune our voice to our minds, not the reverse? There is an exception: when our voice carries the Word, the Logos. To understand, it is helpful to read what St Benedict’s rule 19 for singing the Psalms has been:

CHAPTER 19. THE DISCIPLINE OF PSALMODY We believe that the divine presence is everywhere and
that in every place the eyes of the Lord are watching the good and the wicked (Prov 15:3). But beyond the least
doubt we should believe this to be especially true when we celebrate the divine office. We must always
remember, therefore, what the Prophet says: Serve the Lord with fear (Ps 2:11),and again, Sing praise wisely
(Ps 46[47]:8); and, In the presence of the angels I will sing to you (Ps 137[138]:1). Let us consider, then, how
we ought to behave in the presence of God and his angels, and let us stand to sing the psalms in such a way that our minds are in harmony with our voices.

The Rule of St Benedict (written in 516AD)

Singing the Mass is like singing the Word, or singing the Logos. When we sing the Mass, our minds should be in harmony with our voices. This other excerpt of Vatican II’s Constitution on the sacred liturgy then takes its full meaning:

116. The Church acknowledges Gregorian chant as specially suited to the Roman liturgy