Who is the speaker addressing and why can that person not hear or understand what she is saying?
The speaker is addressing to her husband. That person cannot hear nor understand what she is saying because he is not alive.
What does the speaker promise at the end of the poem? Why do you think the speaker does this?
At the end of the poem, the speaker promise her husband to meet him in their next life.
I think speaker loves her husband so deep that she doesn't want to be apart even in their next life.