One of the largest complaints that many students and professionals have in their day-to-day lives is the sheer volume of text that needs absorbed. Whats the problem? The problem is that the average reader only reads at around 200 words per minute. For short sections of text this is fine, but longer texts become intolerably time-consuming.
No? Don't be surprised. Turns out that most Americans, and indeed most of the world, sub-vocalize to some extent. That's natural, it's simply a hold over from when you were originally taught to read. The trouble is, after we learn to read, very few people rarely improve upon the basic reading skills we're as children.
From the moment a baby is born parents and medical professionals alike are watching that the child meets certain agreed upon milestones in their development. While there is some acceptable variation, certain general guidelines have been set. One of the main milestones that is monitored in small children is the development of speech skills.