Psalms 89:15 - Matthew Poole's English Annotations on the Holy Bible

The psalmist, intending to describe the doleful estate of the royal family and kingdom of Israel, aggravates it by the consideration of their former felicity. That know the joyful sound, i.e. who enjoy the presence of God and his ordinances, and the tokens of his grace and mercy to them, to which they were called and invited by the sound of trumpets, which upon that only reason was very pleasant and grateful to the Israelites. See Numbers 10:9,10. So the sign is put for the thing signified, as is manifest, both from the following clause of the verse, and because otherwise the hearing of the outward sound of trumpets could never make them blessed. Walk in the light of thy countenance; they live under the comfortable influences of thy grace and favour; whereof at present we are bereaved.