Fourteen years ago, I blogged about the future of voice. In the post, I asked these two questions - which I'd nicked from someone else:
- Are you faster at speaking or typing?
- Are you faster at reading or listening?
Lots of us now use Siri, Alexa, Bixby, and the like because it is quicker to speak than type. For long-form wordsmithing - it's still probably easier to type-and-edit than it is to speak-then-edit. And the way humans speak is markedly different from how they write.
But the bottleneck has always been that listening to speech is slower than reading text.
The average reading speed is around 238 words per minute. Obviously there are a lot of caveats around the age of the reader, the difficulty of the material, whether one is reading for leisure or work. But it will do as a comparator.
The average speaking speed is around 150 words per minute. Again, that depends on the age of the speaker, urgency of their talk, familiarity with the language, and so on.
Therefore it is faster to read academic papers rather than to listen to academic lectures. Case closed!
There's a fascinating new paper out -
Here's the quote I found most interesting - with emphasis added:
Collectively, the present experiments indicate that increased video speed (up to 2x) does not negatively impact learning outcomes and watching at faster speeds can be a more efficient use of study time.
Thus, as long as to-be-remembered information can be effectively perceived and encoded, learning outcomes may not be affected by playback speed.
However, previous work has indicated that speech comprehension begins to decline at around 275 words per minute (Foulke & Sticht, 1969; see also Goldhaber, 1970; Pastore & Ritzhaupt, 2015; Vemuri et al., 2004) and the videos in the current study exceeded this threshold when played at 2x speed.
Although the elevated speech rates at 2x speed may initially be less comprehensible to students, researchers have been able to train participants to understand speech at rates up to 475 WPM (Orr et al., 1965).
Therefore, with practice, higher rates of speech may not be completely incomprehensible and since 85% of students reported watching lecture videos at quicker than normal speeds (see Figure 3a), they may be better able to process the material as a result of experience.
I guess this shouldn't come as a surprise to me. I tend to watch my MSc lectures at 1.75x with subtitles - and have been doing the same with podcasts and tutorial videos for years. Looks like I am in the majority.
If the average person speaks at ~150 Words Per Minute, increasing playback speed to 1.5x gives a listening rate of ~225 WPM. That's about the same as reading speed.
Going to 475 WPM means listening at 3x normal speed.
My mate Léonie Watson is blind and has written extensively about the use of text-to-speech technology. Because she listens to a synthetic voice, with predictable and consistent pronunciation, she's able to listen at about 520 WPM! That's 3.5x faster than the speech of a biological human.
I'm not suggesting that you can speed-listen your way through any complicated topic and retain perfect understanding of subject and nuance. But it is becoming clear that synchronous teaching has limitations when it comes to efficiently teaching people. There's no substitute for being able to stop an expert mid-lecture and saying "sorry Prof, I don't get that - could you please help me understand?" But the reality is, most people never stick their hand up in class. So listening to lectures on playback - at double speed - is simply a better "user experience" for the student.
Learning, of course, isn't just listening to people drone on in front of a blackboard. The student still needs to do the exercises, write their essays, consolidate their knowledge, reflect on what they've learned, and so on.
But the ability to "speed" your way through a (well edited and professionally recorded) lecture is something to be welcomed. It gives students more time to spend on their studies with, apparently, no ill effects.