In our most recent lesson at St Cecilia’s with Sister Bernadette, we spent some of the time practicing how to sing silence, that is how to observe the break between the half bar line of a psalm verse. For those not familiar with psalmody, the pause comes at the end of the first sentence and not at the end of the verse.
Ideally, sister said, the break should be two beats long, the tempo of the beat being determined by the speed the psalm is sung. One of my choir members always reiterates his old Gregorian chant tutor’s mantra that the gap should be long enough to say, Jesu Maria. Whilst both of theses counting aids are useful. the difficulty arises because you are not supposed to count “one, two” or mutter something under your breath, but as a group you should just be able to sense when to start the second line of the psalm. If your group are singing as one, it comes naturally, apparently…
I am always struck by how beautiful the silence is between musical phrases. The striking contrast from the noise of musical sound to nothingness makes the silence often seem deafening. For me, this is where God really speaks to us, in the pauses and ultimately, in the silence. Sadly, during Sunday Mass, it is too easy to keep the music going, sometimes as a cover to drown out extraneous noise but usually just because we feel uncomfortable with the starkness of silence.
The Catholic liturgy website on silence in the liturgy of the hours:
It is a general principle that care should be taken in liturgical services to see that “at the proper times all observe a reverent silence.”  An opportunity for silence should therefore be provided in the celebration of the liturgy of the hours.
202. In order to receive in our hearts the full sound of the voice of the Holy Spirit and to unite our personal prayer more closely with the word of God and the public voice of the Church, it is permissible, as occasion offers and prudence suggests, to have an interval of silence. It may come either after the repetition of the antiphon at the end of the psalm, in the traditional way, especially if the psalm-prayer is to be said after the pause (see no. 112), or after the short or longer readings, either before or after the responsory.
Care must be taken to avoid the kind of silence that would disturb the structure of the office or annoy and weary those taking part.
203. In individual recitation there is even greater freedom to pause in meditation on some text that moves the spirit; the office does not on this account lose its public character.