Speed vs. efficiency in speech production and reception

Language Log 2019-09-11

An interesting new paper on speech and information rates as determined by neurocognitive capacity appeared a week ago:

Christophe Coupé, Yoon Oh, Dan Dediu, and François Pellegrino, "Different languages, similar encoding efficiency: Comparable information rates across the human communicative niche", Science Advances, 5.9 (2019):  eaaw2594. doi: 10.1126/sciadv.aaw2594.

Here's the abstract:

Language is universal, but it has few indisputably universal characteristics, with cross-linguistic variation being the norm. For example, languages differ greatly in the number of syllables they allow, resulting in large variation in the Shannon information per syllable. Nevertheless, all natural languages allow their speakers to efficiently encode and transmit information. We show here, using quantitative methods on a large cross-linguistic corpus of 17 languages, that the coupling between language-level (information per syllable) and speaker-level (speech rate) properties results in languages encoding similar information rates (~39 bits/s) despite wide differences in each property individually: Languages are more similar in information rates than in Shannon information or speech rate. These findings highlight the intimate feedback loops between languages' structural properties and their speakers' neurocognition and biology under communicative pressures. Thus, language is the product of a multiscale communicative niche construction process at the intersection of biology, environment, and culture.

Final paragraph:

To conclude from a broad evolutionary perspective, we thus see human language as inhabiting a biocultural niche spanning two scales. At a local scale, each system consisting of a given language and its speakers represents one instantiation of a cultural niche construction process in a specific context involving the ecological, biological, social, and cultural environments. At a global scale, all of these language speakers' local systems are subjected to universal communicative pressures characterizing the human-specific communication niche and consequently fulfilling universal functions of communication essential for the human species

Here are the languages analyzed:

Austroasiatic [Vietnamese (VIE)], Basque [Basque (EUS)], Indo-European [Catalan (CAT), German (DEU), English (ENG), French (FRA), Italian (ITA), Spanish (SPA), and Serbian (SRP)], Japanese [Japanese (JPN)], Korean [Korean (KOR)], Sino-Tibetan [Mandarin Chinese (CMN) and Yue Chinese/Cantonese (YUE)], Tai-Kadai [Thai (THA)], Turkic [Turkish (TUR)], and Uralic [Finnish (FIN) and Hungarian (HUN)]

The paper itself is highly technical and involves a considerable amount of mathematical computation, so it might be easier for some readers to approach it through this article by Rachel Gutman:

"A Rare Universal Pattern in Human Languages:  Some languages are spoken more quickly than others, but the rate of information they get across is the same", The Atlantic (9/4/19)

Gutman's explanation of the relationship between sound and information transmission is helpful, at least for me:

Informativity in linguistics is usually calculated per syllable, and it's measured in bits, just like computer files. The concept can be rather slippery when you're talking about talking, but essentially, a bit of linguistic information is the amount of information that reduces uncertainty by half. In other words, if I utter a syllable, and that utterance narrows down the set of things I could be talking about from everything in the world to only half the things in the world, that syllable carries one bit of information.

Of course, there is a great deal of individual variation in the speed with which different people speak the same language, but the overall tempo of a given language is similar across the population of speakers of that particular tongue.  Nonetheless, as an example of someone who spoke with phenomenal rapidity, I may cite a village magistrate in Nepal whom I met in 1965-67.  It was almost comical how fast he spoke.  Every syllable was spoken distinctly, but they were uttered so quickly that they went by in a blur and it was very hard for me to absorb much of what he was saying, although halfway through my two-year stay in Nepal I had become completely fluent in Nepali and was capable of carrying on fully intelligible conversations with most speakers at normal speeds.  Instead of trying to understand what the rapid-fire village magistrate was saying, I would just stand there with an amazed, quizzical look and marvel at how his tongue and lips could produce such a machine gun stream of syllables.

Reacting to the above-cited article, June Teufel Dreyer, herself hailing from N'yawk, remarks:

New Yorkers are frequently teased for speaking too quickly, just as Southerners are for speaking so slowly.  Could it be that other people's brains are absorbing only a certain amount of what New Yorkers are saying, since the article implies there are certain limitations on the brain's processing abilities?

A college friend and fellow New Yorker once opined that in New York you have to talk fast because you know that people there will stop listening after 30 seconds.  I thought, "that makes sense."

Summary wrapup of the Sciences Advances paper:

This is a report of measurements of how much information speakers of various languages typically transmit in a given period. A total of 17 major languages were studied and while it was found that there was wide variation in the speed of talking as measured in syllables per second, the "faster" languages (e.g., Japanese) had lower information content per syllable than the "slower" ones (e.g., Thai) and that as a result all had very similar average rates of information transmission — just about 40 bits per second.  The hypothesis is that this represents inherent limits in the underlying language processing in the human brain that is common to all languages.

Personally, whenever I'm talking to someone else, no matter in what language, I occasionally wish that they would either slow down or speed up.  In other words, I have a distinct comfort zone for absorbing information from the person with whom I'm conversing.  Sometimes I feel like saying to them, "Spit it out, my friend", and sometimes I want to tell them to slow down a bit.  On the other hand, I'm sure different auditors feel the same way about information I'm conveying to them.  Most of the time, however, a truly satisfying conversation results when interesting information is being exchanged at a relaxed rate.

[h.t. Chiu-kuei Wang]