Your understanding, measured live

Open any episode in Riff and the first thing you see is a number: how much of that episode’s vocabulary you understand right now. Under it, a coverage bar sorts every word into Seen, Tried and Known, and a six-stage comprehension profile climbs from Lost to Mastery as the number grows.

We put a number on it because comprehension research does too. Lexical coverage, the share of running words you know, is one of the best-studied predictors of whether you can follow speech. For listening, research places adequate comprehension around 95 percent coverage, with many listeners already coping at 90. A 2024 study brought this to television itself, swapping words in documentaries for invented ones: 90 percent coverage was enough to follow adequately, and 95 made viewing comfortable, because the picture carries part of the meaning.

Riff’s profile anchors sit on those two research numbers: Comfort begins at 90 percent and Fluent at 95. The earlier bands, like Grasp at 84, are our own design choice, there so progress shows up long before comfort does.

The stage names are ours. The anchors come from the research.