One of the confusing things about autism, and about cognitive disabilities in general, is that something that seems like the same problem from the outside can actually be caused in several different ways. I already talked about the difficulty I have with conversation because of auditory processing, but difficulty with language, regardless of medium, can also be an autistic thing. (As a general rule, I’ve found, there is no limit to the variety of oddly specific things the human brain can have trouble with. Suspend your disbelief.)
Some autistic people have trouble using language, any kind of language, which is separate from any problems they may have with hearing or vision (or with the physical abilities required to speak or write). Some say that they simply don’t think in words, and translating their thoughts is complicated. Some find one form of language easier than others— e.g. they understand written words better than spoken words, or they can use sign language fluently but have trouble speaking with their voice. It is entirely possible for a person’s brain to be better at spoken language than other forms of language, but autism tends to be associated with difficulty speaking or understanding spoken words. A delay in learning to speak as a child used to be one of the main criteria for autism, although it isn’t necessary for diagnosis anymore.
Apart from my trouble with background noise, I don’t generally have difficulty understanding other people’s words or writing (what are called “receptive language” abilities) but I do have trouble putting my own thoughts into words (“expressive language”). One clue that I have problems with language as well as with hearing is that background noise, especially noise that involves people talking, not only makes it hard for me to hear, it makes it hard for me to read and write, too. The words I’m hearing seem to override the ones I’m reading, or writing, or trying to compose in my mind. I often can’t help but listen— and forget what I was thinking— even if what I hear is as unimportant as a TV program I don’t want to watch, or a stranger’s conversation in a restaurant.
I also find it hard to speak when I’m tired (especially when I’ve been socializing, listening and talking a lot) and I’ll sometimes only speak to briefly answer questions. I don’t often reach a point where I can’t talk at all, and usually that doesn’t last very long for me, but the truth is I have more trouble with expressive language than I seem to. Because the things I do say sound reasonably normal, people assume I’m naturally shy or quiet, when the truth is that putting my thoughts into words fast enough to keep up with a conversation is difficult for me.