Priscilla,
Please don’t fertilize!!
My guess is that your tree is suffering from transplant shock. It’s roots are just getting used to their new home. The likely need water, but not a flood.
Just by looking at the ground around your trees, it looks dry and gravelly. If this were my tree I would try watering around the tree and not just by its side. A more moist soil will provide a more consistent supply of moisture to the roots. A bunch of water dropped right by the tree will soak, them dry out as the rest of the dry ground competes for the water you applied.
I think that mulching is warranted, but perhaps not right up and next to the tree trunk, as you don’t want any mold or mildew issues on the
wood itself while the tree is distressed.
Sadly, you may lose your foliage, but this does not mean that the tree is dead. The tree may well recover once the root is established and can support foliage, but for the meantime, the tree may be shedding its foliage as a way of saving the root.
Give it some TLC and be patient. While I don’t think singing will help, giving it other attention may do wonders.
Good luck and please keep us updated,
Eric