Researchers from the Université de Lyon recruited 59 male and female volunteers who were native speakers of one of seven common languages — English, French, German, Italian, Japanese, Mandarin and Spanish — and one not so common one: Vietnamese, to analyze the speed of spoken language.
The results are very interesting. Although some languages like Japanese and Spanish are spoken at a faster tempo than others such as Mandarin and French, the amount of semantic information transmitted is almost identical.
The determining factor in terms of speed is how packed with meaning each syllable is. Japanese syllables are very sparse in meaning whereas each syllable in Chinese is normally packed with meaning, so where a Japanese speaker would sprint, a Chinese speaker would stroll, and in the end, they will transmit the same amount of information in a given period of time.
English, with a high information density of .91, was spoken at an average rate of 6.19 syllables per second. Spanish, with a low-density .63, sped along at a syllable-per-second velocity of 7.82.