An interesting article, Shaumik.
With the growth of speech-activated devices (Kinect, Siri, Cortana, etc), would you group speech defects as accessibility issues? Sometimes these aren’t due to cognitive or neural issues; they could be caused by physical damage (vocal cord damage, muscle weakness, respiratory weakness, etc.), or could well be a limitation of the software itself (e.g., Siri not understanding a Scottish person saying “Jammie dodger”). It feels logical that we see more applications, and websites, using speech as part of the user experience as it’ll make things like search feel more intuitive and could itself be seen as an assistive technology for people with certain cognitive or learning difficulties.