Why does Chapter III of The Stranger end with "the blood pounding" in Meursault's ears and "the dog whimper[ing] softly"?Different translations may...

The answer to this question is a complex one partly
because of Camus' innovative psychological style and partly because of symbolism and
foreshadowing. Firstly, Camus believed that the psychological aspects of a psychological
novel were revealed in action, which ran contrary to the popular psychological literary
convention of his day that built psychological development through first-person
introspection and monologues of self-examination. What this means is that in order to
show Meursault's psychology and psychological development, Camus develops actions, which
includes dialogue and first-person descriptions of passing moments--but not passing
thoughts.

Secondly, at least one recurring symbolic motif
is present in the passage you ask about:

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The whole building was as quiet as the grave, a
dank, dark smell rising from the well hole of the stairs. I could hear nothing but the
blood throbbing in my ears, and for a while I stood still, listening to it. Then the dog
began to moan in old Salamano’s room, and through the sleep-bound house the little
plaintive sound rose slowly, like a flower growing out of
the silence and the
darkness.

The symbolic motif
I'm thinking of is flower. There are
at least four places in which Camus likens something to a flower, including Marie's
face: "her sun-tanned face was like a velvety brown
flower." The first use of
flower is when Meursault sits in vigil
at his mother's coffin:

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through the open door came scents of
flowers and breaths of cool night air. I think I dozed off
for a while.
I was wakened by an odd rustling in my
ears.

The
flower symbolizes the existential
absurdity in life, the flower appearing as it does in a completely random and valueless
fashion (1) at the side of death, (2) in a poorly lit and ill-smelling stairwell and (3)
in a beautiful woman's face. When, as in the first two uses (vigil, stairwell),
flower appears with the symbolic motif
of sound rushing in Meursault's ears ("odd rustling in my ears";
blood throbbing in my ears"),
existential absurdity is linked directly to Meursault's life, which leads to the next
consideration, that of foreshadowing.

Thirdly, the scene
set by Camus in the ill-lit stairwell--

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"quiet as the grave, a dank, dark smell ... 
blood throbbing in my ears ... dog began to moan ... through the sleep-bound house the
little plaintive sound rose, like a flower growing out of
the silence and the
darkness"

reflects back on
the earlier scene of the vigil at the coffin echoing the funereal motif of death and
decay, with the dog moaning as mourners may do and as Meursault perhaps ought to have
done at the vigil. This foreshadows what will eventually happen to Meursault largely as
a result of the overwhelming influence of his behavior (or lack of behavior) at the
funeral vigil.

So why does Chapter III of The
Stranger end with the "blood throbbing" and the "dog moaning"? It ends thusly
to express Camus' existential views; to tie random meaninglessness with Meursault's
life; and to prepare the reader for--to foreshadow--the events that will ultimately
follow; and to prepare for the great and significant influence the funeral vigil has on
Meursault's ultimate end.