Why is it required to say salām loudly to the dead when we enter the graveyard since the dead can not hear us? Also what about the reckoning in the graves if the spirits go to Barzakh after death?

Saying salām whether loudly or quietly does not mean that the dead are listening to this greeting. It is just a prayer from the living for the dead. We just imagine the dead person before our eyes and talk to him as if he were before us -- whereas he is actually not. This is our common practice whenever we deeply recall a dead person even while sitting at home, isn’t it?

It is evident from the Qur'ān that once a person dies his spirit goes to a place beyond the barrier of Barzakh to a place whose details we know very little of:

Before them is a partition (Barzakh) until the Day of Judgement. (23:100)

Immediately after death, a soul comes to know whether he shall be among the dwellers of Heaven or of Hell. If he is to enter Heaven, he is treated in a grand style and shown his final residing place in Heaven. If he is to enter Hell, he is treated as criminals are before receiving their punishments and shown his dwelling place in Hell. This is a kind of a mental torture for him.

Both these treatments have been referred to in the Hadīth literature as being given within the grave. Actually, in all such Ahādīth, the word `grave’ signifies the world beyond the partition of Barzakh.