I tried to google this, and got some hits that indicate a vague yes, but I need more info for a short story I’m trying to write. Can living through a traumatic experience actually cause you to lose the ability to speak, or is it just the desire to speak? Is it common? Long-lasting? Do you lose all vocal sounds, or just words? How would you get your voice back?
I found this, which might be helpful. There’s also this, which refers to the conditon as “conversion disorder,” which might help in your research. Another term is "hysterical aphonia, " from here, with more scientific info here.
Just from the trauma, or from physical stuff related to the trauma? My aunt lost her voice for years when she screamed at a bad practical joke played on her. It was the scream that did it, but it was caused by the surprise.