Language learning research
Studies we did on real videos, with the data and how we did them.
How long does it take to learn a language? Hours of real video to each level, in 12 languages
We counted every word in 4,500 hours of native video in 12 languages to estimate how many hours of input build the vocabulary of each CEFR level.
How fast do native speakers talk? Speech rates in 44 languages
In native videos, Tamil, Japanese, Turkish, Portuguese, Italian and Spanish speakers say about 6 syllables per second, English and German speakers about 4.7. Measured on 16,293 clips in 44 languages, with the speed by CEFR level, by dialect, and against the classic lab study.
How many words do you need to understand native videos?
With the 5,000 most common English words, the typical native clip is 95.6% words you know. Spanish needs about 6,800 words to reach 95%, and in 13 of 23 languages even 10,000 are not enough. Data from 35,615 native clips, per language and per level.