Ever wondered how Guyver's can vocally communicate? I do all the time. Anyone got any thoughts on how they do it? I know the host's body is altered when bioboosted, so I would like to know how it affected a Guyver's ability to speak. 

I thought that the host wasn't altered and an armored cladding that is the guyver attaches it's self, and exoskeleton. I would guess that the armour has some sort of interface mechanism that replaces a mouth, possibly the same part that produces the sonic busters?

I think that's the primary function of the orbs found at the mouth area. Sound is really just vibrations in the air so the orbs vibrate creating audible noise, the sonic buster is just this function turned up to 11. Because of the new respiratory organ the guyver creates in the neck of its host it's possible that hosts vocal cords are removed to make room for it and they cannot speak normally.