In Exodus 15:1, this signifies the glorification of the Lord on account of liberation from slavery. (Arcana Coelestia 8261)

In Psalm 27:6, represents what is spiritual from celestial love. (Arcana Coelestia 420)

Every affection of the heart has a tendency to produce singing, and so it will produce anything relating to singing. The affection of the heart is celestial, and the singing derived from it is spiritual. 'Singing' indicates the testimony of gladness from the affection for truth.

(Odkazy: Arcana Coelestia 418)

418. The previous verse deals with celestial things, which are the attributes of love, the present verse with spiritual things, which are the attributes of faith. These spiritual things are portrayed as 'the harp and organ'. That stringed instruments, such as harps and others like them, meant the spiritual things of faith is clear from many points of view. In the worship of the representative Church instruments like these, and the singing likewise, had no other representation. This was why there were so many singers and musicians, the main reason for such representation being that all heavenly joy produces gladness of heart, which was expressed by means of singing, and subsequently by means of stringed instruments that strove to match the singing and uplifted it. Every affection of the heart also has this capacity to produce singing and therefore the things which go with singing. Affection of the heart is something celestial, singing issuing from it something spiritual.

[2] That singing and the like means that which is spiritual has also become clear to me from angelic choirs, of which there are two kinds, celestial and spiritual. From the vibrant quality of their singing, to which the sound of stringed instruments may be likened, spiritual choirs are readily distinguished from celestial choirs. This will in the Lord's Divine mercy be described later on. What is more, the most ancient people related that which was celestial to the province of the heart, and that which was spiritual to the province of the lungs. In so doing they related that which was spiritual to whatever involved the lungs, such as singing voices and other similar things, and so to the voices or sounds of such instruments. The reason for their so relating them was not only that the heart and lungs represent a kind of marriage, like that of love and faith, but also that celestial angels belong to the province of the heart whereas spiritual angels belong to that of the lungs. It can also be recognized that such considerations are meant here from the fact that this is the Word of the Lord, which would contain no life at all if its message were merely that Jubal was the father of those who play on harp and organ. Nor would any use be served in anyone's knowing it.