The big irritant is his absurd claims about adult learning capabilities. When I...
You = personal experience of one.
Him = personal experience of one + research + more research + claims he's looked for counter studies
Benny 1 - Sean 0
You = personal experience of one.
Him = personal experience of one + research + more research + claims he's looked for counter studies
Benny 1 - Sean 0
Here it is the case: My Chinese wife is a perfect French speaker but she still can't hear or pronounce the difference between "gato" and "cado". I work in Chinese, in a 100% immersion, and tones are still not natural to me. And our bi-cultural kid, at 3, has better tones than me, and has no problem with d and t, or g and k.
I won't look hard for papers but I would be surprised if none has ever "proven" that babies hear and execute the full palette of sounds, and learning a language specializes (by narrowing) this skill, removing parts not used in the context to differenciate meanings.
Don't be willing to make an argument against all science while trying to win one discussion. Just give your anecdote and let people take it as they will.
Babies and pre-pubescent children do indeed have a distinct advantage when it comes to learning sounds, tones, and pronunciation for a language [1][2]. It's also been observed that children are more likely to sound native (in language 2) if they move to another country and learn that second language prior to puberty (see again, Nagle [2]). So, gbog, if your child speaks/hears French, Chinese, and English regularly before hitting puberty, he/she will likely sound native in all three languages. But this advantage doesn't nullify the claim that adult learners can still become fluent in a foreign language. It just means that adult learners might never sound exactly like a native speaker, even though motivated learners can achieve near-native pronunciation in their target language [3].
[1] Babies are born with the ability to hear/distinguish between the sounds of all world languages, but this ability starts to diminish around the age of 10 months (pp 39-40, The Bilingual Edge, King and Mackey, http://www.amazon.com/The-Bilingual-Edge-Second-Language/dp/...).
[2] "Critical period research clearly demonstrates that the probability of a near-native L2 phonology rapidly diminishes as we age", Charles Nagle, "A Reexamination of Ultimate Attainment in L2 Phonology: Length of Immersion, Motivation, and Phonological Short-Term Memory", http://www.lingref.com/cpp/slrf/2011/paper2913.pdf
[3] "The results of this study highlight the fact that learners appear to be able to achieve near-native pronunciation without significant formal instruction in pronunciation which perhaps also evidences the role of implicit learning in L2 phonology...", Nagle, http://www.lingref.com/cpp/slrf/2011/paper2913.pdf
Have a look at (Harvard linguist) Steven Pinker's book The Language Instinct. It gives a great overview. Or if a book on linguistics isn't your thing, then read the recent studies on critical period hypothesis for SLA, such as Mayberry and Lock, 2003.