[RcouF1uZ4gsC]

> The slower ~100 wpm (i.e. 1x speed) acted as a barrier to learning.

Unless there is a lot of good evidence, I am skeptical of this claim

Human children are exposed verbally to 1x human speech. Do we really think that making teachers talk faster will improve learning and retention?

Also, according to linguistics, I believe pretty much human languages transmit close to the same bit rate (some languages have longer more descriptive words, some have shorter words, but by and large they average out).

Throughout our evolution, we have been exposed to 1x speech.

My guess would be that are brains don’t have a learning block to 1x speech.

[RobMurray]

It maybe doesn't come naturally to most people to be able to take in information from speech at high speeds, but it is definitely possible to learn. I am blind, and use a screen reader. My screen reader's voice is many times faster than normal human speech. (I don't know exactly how much faster, but most people can't understand a word of it.) I also listen to non-fiction podcasts and books at 1.5-2x speed, although I almost always listen to fiction at normal speed unless the reader is painfully slow.