Stealth Speaker (3.5e Feat)

Balance: To put this down to Rogue level, split this into two feats: A feat that gives the level 1 and 5 abilities, and a second feat that has the first as a prerequisite and gives the level 10 and 15 abilities. The level requirements stay the same, but you get a -10 penalty to the Move Silently checks, the DC of the Spot check is only 15, and completely de-somatizing or de-verbalizing a spell reduces your Wordcasting check by 1 each for the spell.