When you speak the second syllable of the word of unmaking, you alter a creature's truename to erase on of its senses. The reverse effect is the same, but it is caused by overstimulation.

You remove one of the target's senses: sight (see blinded), hearing (see deafened), smell (negates scent ability), or touch (-4 circumstance penalty on attack rolls, Acrobatics, Athletics, Disable Device, Search and Use Rope checks).