Today, we read and we listen. The University of Houston presents this series about the machines that make our civilization run and the people whose ingenuity created them. 

I've taught all my adult life. That's meant constant writing and speaking. And I'm still learning how hard it is for a hearer, or a reader, to digest what I write or say. 

So many problems: Take the rate we absorb words through our eyes or ears. Most educated adults read around 300 words a minute. But we absorb clear speech at half that speed – maybe 160 words a minute. Those numbers vary. A lot depends on how much we actually absorb. Sure, we all know reading athletes. Some people can read a thousand words a minute. But they don't do that with technical papers. Auctioneers might speak 300 words a minute. But again: the content's very simple.

Our aim is for people to understand what we write or say. So here's a helpful tool: It's the Flesch Reading Ease Test. Give it a try some time. It's only one of many such tests. Some aim at specific kinds of writing. But any such test tells us pretty much the same thing. And we can just click on the Flesch Test if we write in Microsoft Word.

It tells us the school grade where our writing would suit students best. We get high readability by writing short sentences and paragraphs, using short words, and avoiding the passive voice. The catch is, no one after age four wants to hear "Dick and Jane chase the ball," over and over. Simplicity can quickly get boring. But it doesn't have to.

So to begin, we should know what grade level is right for our audience. Suppose we have college degrees: Does that mean we should be reading at grade level 16? Well, just try it. We'll tire very quickly. I try to keep my own technical writing at grade 10. That might sound like talking down to readers. It's not. It's just getting obstacles out of their path. How to do that?

Well, we don't ask readers to decode a lot of compound sentences. It means each paragraph holds just one thread of thought. Avoiding big fancy words when we can just as well use simple ones is not dumbing down. It's just being merciful to readers.

But what about listeners? We process spoken words far more slowly when we hear them. A sentence enters our mind in one gulp when we read. But it takes a few seconds to hear a spoken sentence. That taxes our short-term memory. Spoken sentences have to be easier to digest. And, when you and I converse we talk that way without thinking about it.

So: here's something you'll find shocking: What grade level have I been speaking here? The answer is Third Grade! So: Have I been dumbing down for you? I have not. I know that you're just as smart as anyone. But I also know that you might be driving a car, or jogging, or making the bed.

Of course, some people will frown at what I'm up to. But that's okay. After all, you're the one who matters. And you are still listening. 

I'm John Lienhard at the University of Houston, where we're interested in the way inventive minds work.

The Wikipedia page on Readability gives a very complete account of the problem of readability and the many measures of it.

See also the Wikipedia page on the Flesch Test.

If you have trouble connecting with the Flesch Test in Microsoft Word, this online page will run the Test of any sample of text

Here is an interesting analysis of rates of public speaking. (Notice that speech has to be slower when it is not supported by any visual cues.) 

Suppose you have a master's degree. Does that mean that you should be able to read at 18th grade level? Here, for the fun of it, is the abstract of a technical paper, written at that level. I think you will agree that it would try the patience of a genius:

It is shown that for a dynamical system admitting wave propagation modes (i.e. a wave-guide) the cross-power spectral density for stationary random fluctuations in the system will be dominated by the waves if they are lightly damped, the reason being that these can correlate over large distances of the order the inverse of the damping ratio. For a turbulent shear flow the wave propagation constant is obtained approximately from the solution of the Orr-Sommerfeld problem for the mean flow. Numerical calculations for a flat-plate boundary layer produce results for the streamwise dependence of the cross-power spectral density for the surface pressure fluctuations in good qualitative and quantitative agreement with measurements. An exception is the convection velocity for which the theory predicts a value that is somewhat too low.

Here are two cases from literature: Earnest Hemmingway wrote The Old Man and the Sea at a reading ease grade level of 4th grade. One sentence of Marcel Proust's Swann's Way clocked in at a readability score of -515 (No grade level is associated with such a horrific number.)

The image is from "The Pleasures of the Eye and Ear Compared," American Quarterly Register and Magazine, May 1848, Vol. 1, No. 1.

This episode first aired on January 17, 2020