FROM Time comes a report of a delightful study published in Language. Why does it seem like some languages are spoken faster than others? The answer is that speed depends on the average amount of information packed in a single syllable. It takes people about the same amount of time to read a simple story out loud whether it is translated into English, French, German, Japanese or Mandarin. But the number of syllables that will have been spoken in that amount of time varies; those languages that need more syllables to convey the same story sound faster. Fascinating.
At first blush, I have a guess as to why this would be. Languages that have simpler sound systems (fewer consonants and vowels, no tones, nasal vowels or other such tricks) tend to require longer words. This is because if you only have eight consonants and five vowels, as Hawaiian does, you're going to get lots of homophones. So words have to be longer to remain distinct; this is the reason that the famous state fish is the humuhumunukunukuapua'a.
But as they say, everyone gets only the same 24 hours in a day, so it's little wonder that the lower-information-content syllables have to come at a faster rate. Though I don't have counts of their phonemic inventories to hand, it seems little wonder that Japanese, with a fairly simple sound system, was the fastest in the study, and Spanish was second. The "slowest" language, Mandarin, partly thanks to the four tones, has around 2000 possible syllables, far more than Japanese or Spanish.
(This post briefly mis-stated that the study appeared in Nature, not Language.)