You can’t speak. This may be psychological or physical, but it’s persistent and not something you’ll just get over. You can communicate using sign language, writing, or a computer, but not your own natural voice. There’s something to be said for body language, but a lot of meaning can be lost without vocalization. Penalties are at the discretion of the GM for interpersonal skills where spoken communication is important. You also can’t shout warnings to your comrades in battle.