Are the below words a noun or a verb?

hear, America, singing, carols, mechanics, carpenter, plank, beam.

They go in this passage.

I hear America singing, the varied carols I hear;
Those of mechanics – each one singing his, as it should be, blithe and strong;
The carpenter singing his, as he measures his plank or beam,

–“I Hear America Singing,” Walt Whitman