VI · Audio-first drills
Lingu
Flow
An audio-first German drill app for hands-free shadowing practice. Hear a word, pause, hear its translation, loop, backed by an AI-generated CEFR curriculum with studio-quality text-to-speech across 4,000 rows.
Reading-based vocab apps require full visual attention, so drilling on a commute or while doing chores was not possible. I wanted to practise German hands-free, entirely by ear.
A mobile-first audio player that loops through German words and sentences with a configurable pause and an optional English translation. Press Space to play or pause, auto-advance through a category, and an immersive fullscreen UI that fades away during use.
Behind it, a three-stage content pipeline. Gemini generates CEFR A2-structured vocabulary and sentences that enforce correct grammar coverage per word, Google Cloud Text-to-Speech renders studio-quality German and English audio, and a batch script uploads it all to Firebase, producing 43 categories and over 4,000 audio-backed rows.
An earlier prototype had live AI text-to-speech, voice-gender toggles, and a daily-goal streak system. Cutting the gamification and pre-rendering the audio instead of generating it live made the final app faster, cheaper to run, and focused on the one thing that mattered: hands-free repetition.