Why do all the Guado except Trommel have an echoey voice?

Fool! To return to Macalania a traitor! Traitor! Find your salvation on the Farplane.

A line all too familiar to those who struggled with Dark Shiva, but why does his voice echo like that? While he is the only non-Seymour/Trommel Guado i remember hearing voice of, in battle when you kill a Guado they make an odd noise too, similair to Dark Shiva man. Am i looking to deeply into this or is there a real reason?

I didn't mention Seymour as he is half-human so that's reason enough for me, and Trommel does have a weird voice but it still sounds normalish.

They say if you find the answer you get a Dress Sphere in X-2 which let's you kill Mega-tonberries since they are invincible otherwise!!