docs: add v2 release note (rebuilt 3x speed-only; v1 deprecated, tonal-contamination fix)

README.md

@@ -24,6 +24,21 @@ configs:
 
 # NE ASR Augmented Dataset -- Kokborok (trp)
 
+## v2 (2026-05-29): rebuilt 3x speed-only
+
+The previous **v1 (5x)** revision applied +/-1 semitone pitch-shift augmentation to the train split. **trp (Kokborok) is a tonal language with 2 phonemic tones (H/L)**; pitch-shift augmentation corrupts the tonal contrasts the model must learn. **v1 is therefore DEPRECATED and should not be used for training.**
+
+v2 specs:
+- Augmentation: **speed-perturb only** (factors per `configs/augmentation_config.yaml` v2 spec: 0.9, 1.0, 1.1).
+- Aug factor: **3x** (was 5x).
+- Train rows: **7,533** (= 2,511 x 3).
+- Val / test: **unchanged from source** (no augmentation on eval splits).
+- Source: [`sulabhkatiyar/ne-asr-trp`](https://huggingface.co/datasets/sulabhkatiyar/ne-asr-trp).
+- Tonality fix per `.claude/reports/module6/tonal_audit.md` (root-cause: `configs/augmentation_config.yaml` previously flagged `trp.tonal: false`; corrected to `true` on 2026-05-29 commit `06f9b14`).
+- Rebuilt by: `scripts/augment_data.py --config configs/augmentation_config.yaml --lang trp --clean` (Phase B.5.2).
+
+---
+
 Augmented automatic speech recognition dataset for **Kokborok** (`trp`),
 a Tibeto-Burman language spoken in Tripura, India.