greek ethymology of barbar?

hi together,
ist there a well , precisely ethymology of the greek
word "barbaros" ?I should see the sufix "os" is typicaly a greek
sufix but nothing more.
I just ask it because i should like to see if there is any connection
with the neighbours people of the greek in balcans, the shepperds,
which use their words for driving the sheeps with the words "ba^r"
or "bi^r".
It seems to be a logical explanation for the people who use "bi^r"
or "ba^r" due the fact they are allways driving thier sheeps in the
vicinity of the greek,so very easy to call them them the "ba^r"
or "bi^r"-people.
The question is on the second "bar" is this just a normal repeting of
the "ba^r" or does it mean something els?
Any reply would be kindly appreciated.

best regards

a. moeller