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

The
answer to this question is a complex one partly because of Camus' innovative psychological style
and partly because of symbolism and . 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:

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 Salamanos 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:

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--

"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 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.