Our Gemara on Amud Beis discusses the halakhic status of a mute person:

אָמַר רָבָא: אִלֵּם וְאִלֶּמֶת בְּנֵי דֵעָה נִינְהוּ, וּפוּמַּיְיהוּ הוּא דְּכָאֵיב לְהוּ.

A mute man and woman do have intellectual capacity. Rather, it is their mouth that hurts them. Mute individuals have full intellectual capacity; they merely lack a means of expression. 

This Gemara is possibly also making a metaphoric point.  There are people who are quiet, and we assume it is because they are lacking in intelligence or have nothing to say.  However, the Gemara is telling us, they may have a lot to say, it just hurts for them to speak.  There are certain people for whom we must go the extra mile and help them find a way to express themselves; we should not rationalize their silence.

One of my father’s Z”L practices as mechanech was that when he would call on students, he would allow them to raise their hands for the first 30 seconds. He did this mindfully so as to allow the students who thought more slowly, or needed more time to organize their words, to have a chance to join the discussion.  He did not want the quick thinkers to overshadow and monopolize the class conversations and dialogue.  

But this is only one example. There are also people who are shy, who suffer from trauma, and who lack social standing.  There is an ethic in chazal based on a verse in Mishle (31:18) that one must help the mute express himself.  It is even reflected in halacha whereby though a judge must be careful not to show bias nor advocate for a particular side, if he sees the person is having difficulty expressing himself because he is nervous or cannot organize his thoughts, he may “judiciously” offer him help (see Shulkhan Arukh Choshen Mishpat 17:9).

Which brings me back to another childhood memory about my father, Z”l. He would tell me that when he went with his mother to the Liebedige Chicken Market back in the 1940’s, there was a deaf mute fellow whose job it was to pluck the feathers off of the freshly slaughtered chicken.  In those days there was no OHEL Bais Ezra, so this was about as good a job as this poor fellow could get.  He remembers how this man would gesture and grunt animatedly to his mother, as if he was telling her his life story, although of course she did not understand one single word of his gibberish. However, every Friday, she would engage in “conversation” with this man as if they were best friends.  So I suppose my father learned early on how to help the mute speak.