Deaf
Deaf is a disease that can be gained when a flashbang detonates in 8-square radius or nearer or sometimes when the character hears a noise with volume over or equal to 150. In both cases, the duration is based on distance to the source of sound and its volume. In the latter case, the duration cannot be longer than 40 turns.
Deafness can be prevented by Enhanced Hearing bionic.
When deaf you cannot talk to NPCs.
Players can be in significant risk of long lasting deafness if they are in a burning building, since the sounds of the collapsing can be really loud and stack.