> I was wondering if anyone could explain how free accent comes about
> in languages. In particular, what processes lead to English and
> Russian having free accent?
"Free" does not mean "random". In both English and Russian the accent is
on a particular syllable because of a long period of phonetic, analogical
and morphological changes. "Free" in these languages means only "not
predictable from the surface structure of the word". But even that is not
totally true - in English at least, a reasonable first guess can often be
made.
Analogical and other pressures lead to differences in accentuation between
US and UK English (eg "capillary"). UK speakers tolerate two unstressed
syllables after the stress more freely than US speakers do, and I believe
the verb/noun accent pattern ('record / re'cord; 'garage / ga'rage) is more
widespread in one than the other.
Peter