Four principles, decades of evidence.

The principle

You acquire a language by absorbing content you can almost understand — roughly 90% familiar, 10% new. Too easy and your brain ignores it; too hard and it blocks. Krashen called this sweet spot i+1. The US Foreign Service Institute uses the same principle to bring diplomats to professional fluency in 600–2,200 hours.

In Steep

Every native-language sentence is paired with a sentence in yours. The original audio is the L2 input; the translation gives you the 10% you'd otherwise miss. Any video — even one well above your level — becomes i+1.

What you'll feel

You can put on a video about cooking, gaming, philosophy — even one made for natives — and actually follow it at intermediate level. No more giving up after thirty seconds because the speaker is too fast.

The principle

When the original audio and its translation arrive in the same beat, your brain maps sound directly to meaning — no conscious translation step. Marie Atamian taught herself four languages this way in the 1960s; hyperpolyglot Alexander Arguelles popularized it. It's the engine behind Glossika and LingQ.

In Steep

Strict sentence-level alignment, played as audio. You hear the L2, then the L1 — no pausing, no looking up. The stream keeps moving; your brain handles the matching.

What you'll feel

Around month 2, you start predicting the L1 before it plays. Around month 4, on familiar topics, you skip the translation entirely.

The principle

Repeating audio immediately after hearing it builds the muscle memory of speech — the part of fluency that doesn't develop just from listening. Standard training for simultaneous interpreters since the 1960s; used in the American Translators Association certification path and university interpretation programs worldwide.

In Steep

One tap loops the current sentence. The original plays, you repeat in the gap. Built into every session — no separate drill app, no flashcards interrupting the flow.

What you'll feel

Your accent and rhythm tighten noticeably in 4–6 weeks. You stop pausing mid-sentence to think about pronunciation. Words come out at speed.

The principle

Anxiety, embarrassment, and forced output block acquisition at the neurological level — repeatedly shown in classroom studies and reinforced by neuroimaging. The more pressure, the less your brain absorbs. It's why babies acquire so easily, and why grindy textbook learners so often plateau.

In Steep

No quizzes. No streaks-as-shame. No forced output. You listen, you can repeat if you want, you stop when you want. The whole interface keeps you out of perform-mode and in absorb-mode.

What you'll feel

You actually want to open the app. You don't feel guilty when you skip. Your brain stays in the state where acquisition actually happens.