Explain the theme of the poem "The voice" in full details giving also some circumstances

In the poem "The Voice," Hardy is speaking of his dead
wife, Emma.  He is imagining that he hears her voice calling to him, not once, but
repeatedly, on the wind.  He believes she is telling him that she has returned to the
way she was when they first met.  He looks for her to appear to him, not as she was when
she died, after many years of marriage, but in the newness of their days: he recalls her
youthful image even down to the blue gown she wore; and has a vision of her waiting for
him in town.

He misses Emma in his soul.  He fears that
what he hears is not her voice calling to him on the wind, but that she is truly no
more—forever lost to him—and will never be heard from again.  Does he question the
reality of an afterlife here, or simply point out the obvious limitations of death,
separating us from those who have gone before?

At the end
of the poem, he talks about "faltering" forward through the falling leaves, perhaps
referring to the autumn of his own life as he ages.  He wonders if the voice he hears
moving through the thorn bushes (perhaps an allusion to
pain) was simply in his head, and that there is no possibility of
seeing her one more time...though the voice had seemed so
real.

The theme is of loss and
hope—and loss again.  The hope is that the voice is actually hers, not a figment of his
imagination, born of a deep desire to be reunited, coupled with the pain of separation.
 In some ways it is a double-loss he suffers here.  Emma left him the first time at her
death, and now, he imagines she leaves him again, as he recalls the youthful and lovely
girl he fell in love with (perhaps revisiting in his heart the pleasure and excitement
of new love which he has not felt in many years).  In some ways it is a more devastating
loss because for a moment he had thought, hoped, that that young
woman had come to him from the grave and spoken to him, and that in some way, perhaps
they could recapture what has been lost to them.

He cannot
be sure of what—if anything—he has heard, but his acute sense of repeated loss is no
less painful for him to bear.  We get the impression that the love he had for her still
burns as deeply as it had during their life together.