Exactly Helen, approximately 80% comprehension is what I would call listening and understanding (being able to ‘follow along’).
They say the basic equation is based on they’re being next to no similarity between your native language (L1) and the language you’re learning (L2). So, for example, if I listened to 1000 hours of Chinese (which we can safely say shares nothing in common with English except for a few borrowed words which to my mind do not at all sound similar):
1 - (2.71800^(((-.0018)(1000) / (1)) = 0.834670259
then my acquisition of Chinese would be 83%, which is what ALG calls the ‘speaking threshold’, after which students are allowed to start speaking the language, and the point at which fluent speaking starts.
However, for a language like Spanish, which has a language ease (L) of .4 because of the vast similarities between the two languages and the little effort it takes to come to understand a great many words:
1 - (2.71800^(((-.0018)(400) / (.4)) = 0.834670259
then I would reach the speaking threshold (the end of the silent period) after only 400 hours, and in fact I found this was approximately the case while I was living in Spain, as I learned from basically 0 just by listening and without having a class.
Once I reached about this many hours of listening and understanding, which didn’t take very long because my students were constantly talking in Spanish in context in my English classes (that is, they were talking about the content of the class so I had enough background knowledge to follow their conversations) and my roommates would talk to me in easily comprehensible Spanish every day, I got to the point where I felt I was thinking in Spanish and coming up with natural sentences.
I could not have repeated the same feat in China, as I would have picked up on nearly nothing of what my students were saying and had a much more difficult time retaining it even if I had.
So if we take the 1000 hours it took just to reach the speaking threshold of 83% for Chinese and devote those hours to learning Spanish instead:
1 - (2.71800^(((-.0018)(1000) / (.4)) = 0.988885819
then we’ve reached a 98% comprehension of Spanish after the same amount of time.
For further reference check out
http://effortlessacquisition.blogspot.com/2004/10/critique-of-auas-automatic-language.html
I agree with you Helen, you really only need to understand about 80