Why Spanish sounds faster than Vietnamese yet says just as much

Listen to Spanish or Japanese and it seems to rush past; Vietnamese or Thai can sound almost unhurried. Yet when researchers timed 170 people reading the same stories in 17 languages, the fast talkers weren't saying more.

The trick is that each syllable carries a different load. Languages with few, predictable syllables speak quickly; languages with many, dense syllables slow down. Multiply the two and almost every language lands near the same number: about 39 bits of information per second.