I never thought of it either, until it was specifically mentioned to me. Then again, I wasn't exactly in a position to know! :) It makes total sense, looking back, that a bunch of blind teenage nerds like us went for the show.

The exception to the audio description rule was what happened to Carter and Lucy; that scene had very little audible audio, because in-story, the music from the party was drowning events in the exam room out. Someone had to clue me in, and then I went... oh jeez! :( I do remember that they pulled the music from the 'previously, on...' clips at the beginning of the next episode, so you were able to hear what went on, including a badly-injured Carter realizing Lucy was also down. Shudder.

To this day, I can't hear that song without flinching. True story.