Vaani is an 18-layer acoustic pipeline for IELTS/TOEFL speaking. It measures your formants with Praat, your rhythm with peer-reviewed metrics, your grammar with syntax trees — then cross-validates all three against 8 calibrated Indian L1 profiles. No LLM in the scoring loop. No GPU. Same audio = same band, every time. When 2+ layers agree on L1 interference, confidence goes up. When they don't, it's flagged. Vaani tells you what it measured, how confident it is, and what it couldn't measure.
