How does Coleridge use sounds to show that the bodies on the ship have "spirits blest" on them?

Basically after the night, with all its torments, ended the zombie crew begins to sing with angelic voices,

For when it dawned -they dropped their arms,

And clustered round the mast;

Sweet sounds rose slowly through their mouths,

And from their bodies passed.

Around, around, flew each sweet sound,

Then darted to the sun;

Slowly the sounds came back again,

Now mixed, now one by one.