I've read the thread and I hear a lot of for a lack of better word, really un-creative feedback. There are a few things to be taken into factor while considering this.
1. What other skills do you posses.
2. can you communicate non verbally
3. Can you work effectively in a group with out speaking.
4. Do you have a device such as a phone which allows you to express a communication a variety of different areas.
Honestly yes there are careers out there that can be utilized with out the vocal word, and also does not have to be research.
I doubt this is the reason that may has brought this about but psychological trauma may also cause the enablity to speak or the reason of not speaking. Personally i;m a health capable human being who has been effected like this but will not speak through verbal communication but yet still live a awesome life. Please note rose that you can also create your own career based on your own needs just got have the creativity and drive.
Literally googled this and the feed back for was lacking in any type of insight or empathy except for a few unnamed exceptions.
Don't Half A33, care.