This is a collection of quotes from the same chapter, Train Your Ears, Rewire Your Brains, and it highlights one very overlooked aspect of learning a language: listening comprehension. Danish is quite problematic in this regard: a lot of very subtle vowel sound, in a highly vowel-driven language — here is an example from Rhinospike.

This chapter mentions an article with a specific protocol to help adults recognize new sounds. It can most likely be implemented with Anki and recordings of minimal pairs; a flashcard can be designed to have the sound first, and the immediate feedback, as specified in the experiment.

You can’t easily hear the distinctions between the ten t’s [that exist in the world's languages] because you’ve learned to ignore them. Back when you were a baby, you could hear all of them. This made your world a very confusing place. You were surrounded by babbling adults, each of whom had slightly different ways of saying their vowels and consonants. Your ears rang with the sounds of hundreds of different consonants and vowels, and you lay within this chaos, searching for order.

You began to find this order between six months and one year of age. The best data we have on this process come from studies of Americans and the Japanese. By using brain scans, researchers can see whether an individual can hear the difference between any two sounds. An American adult listening to a monotonous “rock … rock … rock … rock … lock” will show a sudden spike in brain activity when “lock” breaks the monotony, but a Japanese adult won’t show any change whatsoever. A Japanese baby, however, has no trouble whatsoever recognizing the two sounds, an ability that gradually vanishes between six and twelve months of age.

It is not that [the Japanese adult] misinterprets what he hears; he literally cannot hear the difference between these two sounds. As far as his brain is concerned, the words rock and lock might as well be spelled the same. In learning English, he is fighting his own brain. How can he possibly hope to succeed?

The most promising research in this field comes from a collection of studies performed at Stanford and Carnegie Mellon. Researchers took a group of Japanese adults, gave them a small wad of cash, headphones, and a computer and told them to sit in a room and listen to recordings of the words rock and lock. Their job was to press a button labeled “Rock” when they heard “rock” and to press a button labeled “Lock” when they heard “lock.” Understandably, their performance was terrible. Even after practicing, it remained terrible. So far, so bad.

Here comes the magic: another group of participants was placed in the same situation, only this time their computer screens provided immediate feedback after each button press. For every correct guess, they saw a green checkmark. For every incorrect guess, they saw a red X. Suddenly, they began to learn. After 3 twenty-minute sessions, they had successfully rewired their brains. On later brain scans, they showed a marked response in the “rock … rock … rock … lock …” tests. They had learned to hear the unhearable.

Rock and lock are classic members of a special group of words known as minimal pairs. These are pairs of words that differ by only one sound, and every language is full of them. I’ve tortured quite a few of my Austrian English students on the differences between minimal pairs like thinking and sinking, SUS-pect and sus-PECT, and niece and knees. These pairs get right to the heart of the hearing problem in a language, and practicing them with feedback provides the best way to train our ears and rewire our brains.