No Robot voice from Malak's mouth cover /sadjawa
Darth Nihilius's doesn't give a muffled mouth sound effect either when talking...
This is exactly right! To be sure, I queried our developers to see if the mask was supposed to have modulation, and they confirmed that it was not designed to modify the voice.
However. This is still a thick hunk of metal over our mouth, and it should change out voice in some way.