According to Robert J. Blake, in Brave New Digital Classroom
"SLA (second language acquisition), the process of learning another language other than your mother tongue (L1), is both an intensive and time-consuming activity. After years of experience in training field agents, the Foreign Service Institute (FSI) estimates that anywhere from 700 to 1,320 hours of full-time instruction are needed to reach a level of high fluency. More specifically, the time committment for learning a Romance language minimally approaches 20 weeks of intensive, full-time study at 30 hours per week, for a grand total of 600 hours, while for other languages, such as Russian and Chinese, the ideal exposure can exceed 44 weeks at 30 hours per week, or 1,320 hours. In stark contrast to these calculations, most university students spend on average only 150 hours per academic year actively studying a second language (10 weeks at 5 hours per week for three quarters = 150 total hourse). Upon graduation from college, students of whatever second language just barely reach the FSI's lowest threshold requirements for achieving proficiency, that of the Romance languages. For students studying a non-Romance language at the university level, four years of second language study are not sufficient to obtain functional proficiency."
Now I know, why after 2.5 years of studying Spanish on my own, through CDs and Internet, and some travel, I still can't understand CNN en Español, movies, and telenovelas! Over the 2.5 years, I have barely accumulated 300 hours. I still need another 300 hours to achieve fluency. That's both disappointing and comforting. I now know where I am, and what I need to do to get where I want to be. But hopefully, the second 300 hours will not take another 2.5 years. Maybe 150 days, six months, or at most a year.