Roger Ellsworth in "Opening Up the Psalms" says not to pronounce the word:
The word ‘Selah’ appears seventy-four times in forty psalms. This word signifies a pause or interlude. It may have been used to inform musicians to change instruments or to call for both musicians and listeners to ponder the truth that had been sung. In the public reading of the psalms, we honour each ‘Selah’, not by actually saying the word, but rather by pausing.
The Believers Church Bible Commentary has a really good summary. Key points:
- The original meaning has been lost
- It has been translated as "Interlude" or "Pause and Reflect"
- It could be a voice signal for louder or raised - in any event, it would be like 'crescendo' or 'rotando' - some form of musical notation.
- Martin Luther, in particular, thought this a signal for deeper meditation.
SELAH Selah (selâ), appearing 71 times in 39 psalms and three times in Habakkuk 3 as a marginal note, is likely a musical instruction. With few exceptions, the term is used in psalms that have titles. The majority of the titles identify the psalms containing Selah with David or the Levitical singers, and about 75 percent of the titles also make reference to the “musical director” or “choirmaster” [Superscriptions].
Translated “interlude” in the LXX, the original meaning is unclear. The three basic interpretations focus on the root sll “lift up”; slh “repetition”; and the Aramaic root ṣl’, “to bow” or “to pray.” Thus, interpreters have suggested that Selah might call for the instruments to enter, raise the pitch or volume, affirm what has been said, or serve as a breath marker.
In addition to suggestions that Selah might signal raising the voice, changing the voices, or increasing the volume, scholars have offered other possibilities. It could be a unit marker in some contexts, as in the paired Psalms 9 and 10. Selah appears at the ends of Psalm 9:16 and 20, marking off verses 17–20 as a unit, almost exactly in the center of the two psalms when they are read as one (Tate, 2004:410–11). Michael Goulder (103–5) has offered the suggestion that it means “recitative,” marking a pause at which there should be the recitation of a prayer or story from Israelite tradition (68:7, 19, 32). Martin Luther referred to Selah as a sign that we are to think more deeply and at greater length what the words to which it is attached mean to say. He called Selah “a punctuation mark of the Holy Spirit. Whenever we find it in the Psalter, the Holy Spirit wants us to pause and ponder; there he wants to touch and enkindle our heart for particularly deep meditation” (Luther, 1956:37).
References: Craigie, 2004:76–77; Goulder: 103–5; Luther, 1956:37; Tate, 2004:410–11.
Finally, The Eerdmann's Dictionary of the Bible points out:
- The 'pause' translation came from the LXX.
- Some scholars via Jerome have suggested it derives from "forever":
Selah (Heb. selâ)
Likely a musical or liturgical notation, occurring 71 times in 39 Psalms and 3 times in the psalm of Hab. 3. In the LXX Selah is rendered as Greek diápsalma (“pause in singing”), suggesting some type of caesura. According to the Targ., followed by Jerome, the term means “forever” or “everlasting.” Perhaps this was a directive to insert a benediction, refrain, or prayer collect at that point. Proposals based on etymology include “voice modulation,” “increase in volume,” “prostration,” and “prayer ritual.” Others have suggested that the consonants of Selah form an acronym for “voice modulation” or “repetition.”
Gerald M. Bilkes