Sanskrit Accents

Dear colleagues,

I am wondering if there are signs of change in the nature of
Sanskrit accent in the following way. Alternations like asti versus
santi, and naumi versus nuva.h are linked to shifts of accent from
the root to the suffix. If these sorts of shifts indicate that an
unstressed vowel gets contracted, or at worst deleted, can one infer
that the accent of Sanskrit in its formative stages was stress
accent, rather than pitch accent as it get represented in Vedic
traditions? Would pitch accent cause the same sort of contractions
of vowels? My second question is this. While the correlation of
vowel contractions with accent shifts is visible in verb forms and
certain nominal paradigms, why is it that there is no similar effect
left in the formation of Sanskrit compounds? Consider the accent
difference between a Tatpuru.sa versus a Bahuvriihi. There are no
vowel alternations similar to naumi versus nuva.h between Tatpuru.sa
and Bahuvriihi. Is it likely that the nature of accent changed from
the stage when forms like naumi/nuva.h originated to the stage when
compounds emerged? Some food for thought.

Madhav Deshpande