Human speech may have a universal transmission rate

Wednesday, September 11th, 2019

Human speech may have a universal transmission rate: 39 bits per second:

Scientists started with written texts from 17 languages, including English, Italian, Japanese, and Vietnamese. They calculated the information density of each language in bits—the same unit that describes how quickly your cellphone, laptop, or computer modem transmits information. They found that Japanese, which has only 643 syllables, had an information density of about 5 bits per syllable, whereas English, with its 6949 syllables, had a density of just over 7 bits per syllable. Vietnamese, with its complex system of six tones (each of which can further differentiate a syllable), topped the charts at 8 bits per syllable.

Next, the researchers spent 3 years recruiting and recording 10 speakers—five men and five women—from 14 of their 17 languages. (They used previous recordings for the other three languages.) Each participant read aloud 15 identical passages that had been translated into their mother tongue. After noting how long the speakers took to get through their readings, the researchers calculated an average speech rate per language, measured in syllables/second.

Some languages were clearly faster than others: no surprise there. But when the researchers took their final step—multiplying this rate by the bit rate to find out how much information moved per second—they were shocked by the consistency of their results. No matter how fast or slow, how simple or complex, each language gravitated toward an average rate of 39.15 bits per second, they report today in Science Advances.


Research in neuroscience supports that idea, with one recent paper suggesting an upper bound to auditory processing of 9 syllables per second in U.S. English.

De Boer agrees that our brains are the bottleneck. But, he says, instead of being limited by how quickly we can process information by listening, we’re likely limited by how quickly we can gather our thoughts. That’s because, he says, the average person can listen to audio recordings sped up to about 120%—and still have no problems with comprehension. “It really seems that the bottleneck is in putting the ideas together.”

I suppose it depends on the content, but podcasts now sound normal to me at 1.5x, and audiobooks at 1.25x.

This naturally reminds me of the language of clear thinking.


  1. CVLR says:

    Out of curiosity, what’s your comfortable reading WPM?

  2. Kirk says:

    Mine’s roughly 800wpm, generic reading. Some stuff I can do faster.

    I’m not sure, though, how you measure this stuff accurately–Do you go by how much of the sentence you read per glance, or by the number of words?

    I was stunned, once, to realize that a lot of people actually read and sound out individual words into their adult years–I think I started reading whole chunks of sentences sometime in my grade-school years, and I’m told by my Mom that she thought I taught myself to read before I started school. My memory of that is different, but I do remember being bored out of my ever-loving mind about every day I was in school. Which probably says a lot about why I am mostly self-taught for subjects past high-school level… My idea of hell would pretty much be a classroom full of “normal learners” and having to put up with going at their pace, yet again.

    Don’t think I was gifted, just able to process information better/faster than average. There’s a certain ineffable difference between bandwidth uptake, processing speed, and raw intelligence. I have known a lot of people who had much slower baud rates than my own, but who were, in my opinion, a hell of a lot smarter than I am. Problem-solving ability doesn’t always imply speed, and speed ain’t smarts.

    Although, I’ve always had a knack for being able to work out implications better than average. I don’t know how many times I’ve looked at something my peers were planning, and went “Yeah, that’s not going to work out well, or at all the way y’all think it will… I’ll give this a hard pass, thankyouverymuch…”.

    This sort of thing is why I’m highly dubious of much of the “conventional wisdom” concerning intelligence. You have to be clear about what you’re measuring, and the lightning-quick guy isn’t always 100% accurate. But, he’ll generally do better on the tests than the slow, methodical plodder who gets every question right–Eventually.

    There’s a place for every sort of thinker, in my opinion. We’ve put way too much emphasis on some aspects of “intelligence”, thanks to unclear thinking on the issue.

  3. CVLR says:

    That’s impressive. I can’t even move my eyes that quickly for an extended period of time.

    I think you’re fooling yourself about “not being gifted”. Your rate of absorption is extraordinary and extrapolation is one of the highest aspects of intelligence.

    In what ways do you think “a lot of people” were “way smarter” than you?

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