Thanks for the comments, Patrick and Bryan.
As a beginner,

I'm looking for consistent simple rules I can rely in, and it sure was
confusing to hear so many different sounds made with "jj" depending on
the context.
for reference:
http://studies.worldtipitaka.org/audio_alpha?page=1&op0=starts&filter0=v%C4%ABriya

is it 4 different contexts? The four words in question all are just
slight variations of "viriyasambojjang", but the jj sounds vary .

I still don't know the answer to whether the "jj" sound in those 4 words
supposed to all sound the same, or slightly different because there's a
context that's too subtle for a beginner to see? Is the variation due to
a Thai accent in the speaker?
Apologies to Bryan if your post explained the answer but I was unable to
comprehend it. I assumed Bryan's explanation referred to words that
varied more radically than very minor variations of "viryasambojjhanga"

-Frank