A renoun authority on Spirituality is Fr. Jordan Aumann who had this to say about vocal prayer, very much in line with St. Teresa of Avila.
Grades of Prayer
We are indebted to St. Teresa of Avila for the clearest and best classification of the grades of prayer. Her concept that the intensity of one’s life of prayer coincides with the intensity of one’s charity is based on solid theology and was confirmed by St. Pius X, who stated that the grades of prayer taught by St. Teresa represent so many grades of elevation and ascent toward Christian perfection.
These grades are (1) vocal prayer, (2) meditation, (3) affective prayer, (4) prayer of simplicity, (5) infused contemplation, (6) prayer of quiet, (7) prayer of union, (8) prayer of conforming union, and (9) prayer of transforming union. The first four grades of prayer belong to the predominantly ascetical stage of the spiritual life; the remaining five grades are infused prayer and belong to the mystical phase of the spiritual life.
Vocal Prayer
By vocal prayer we mean any form of prayer expressed in words, whether written or spoken. This kind of prayer is the form used in public or liturgical prayer,
but it is also much used by private individuals. St. Thomas gives three reasons why vocal prayer is suitable: (1) it arouses interior devotion; (2) it gives homage to God with our body as well as our mind and heart; and (3) it gives expression to the spiritual sentiments that flood the soul in prayer.
Devotion should also be the measure for the duration of one’s personal vocal prayers, for it is futile to attempt to pray well when one is fatigued. By the same token, public prayers should be arranged in such a way that they arouse the devotion of the faithful and do not cause tedium. “In your prayers do not babble as the pagans do, for they think that by using many words they will make themselves heard. Do not be like them; your Father knows what you need before you ask him” (Matt. 6:7-9).
It is not possible to give any fixed rule or detailed directions for the formulas to be used in vocal prayer. Perhaps the best principle to follow is that given for the selection of books for one’s spiritual reading, namely, to use that which is beneficial.
The words by which we express ourselves in vocal prayer will vary with our needs and our spiritual sentiments. Moreover, some persons find it difficult to express themselves, and therefore they make use of the prayers composed by others.
Objectively, the best prayers are the Our Father, which was taught us by Christ himself, the prayers from the pages of Scripture (the Hail Mary, Gloria, Psalms) and the prayers in the liturgy. Unfortunately, their constant repetition readily degenerates into a purely mechanical recitation.
The necessity of fervent recitation of vocal prayer cannot be emphasized too much, because vocal prayer is one type of prayer that can never be omitted completely, even when one arrives at the height of sanctity.
domcentral.org/study/aumann/st/st12.htm