Motivation
Sindhi is one of the most under-resourced languages in Whisper's training data. In testing,
stock whisper-medium almost never produces a correct Sindhi transcription — it frequently
understands the sounds of Sindhi speech correctly, but writes the output in the wrong
script entirely (Devanagari or Romanized text instead of Sindhi's actual script), or
collapses into repeating meaningless characters.
This project quantified that failure and tested whether lightweight fine-tuning (LoRA) on a
small amount of real Sindhi speech could correct it.
Results
Evaluated on a held-out set of 324 human-validated Sindhi clips from Mozilla Common Voice
26.0, fine-tuned on 200 separate training clips using LoRA (~1.2% of the model's parameters
trained):
Table with columns: Metric, Before fine-tuning, After fine-tuning| Metric | Before fine-tuning | After fine-tuning |
|---|
| Word Error Rate (WER) | 148.35% | 72.97% |
| Exact word matches | 7 | 819 |
| Insertions (garbled/looping output) | 1,250 | 124 |
| Substitutions | 1,791 | 1,624 |
| Deletions | 773 | 128 |
Key finding: fine-tuning almost entirely fixed the wrong-script and gibberish-loop
failure modes (insertions dropped ~90%), and the model now consistently outputs real
Sindhi script. Word-level accuracy (substitutions) improved more modestly — with only 200
training clips, the model learned what Sindhi script looks like far better than it
learned precise vocabulary. This is an honest, expected limitation of fine-tuning on a
small dataset, not a fully "solved" result.
Training details
- Base model:
openai/whisper-medium
- Method: LoRA (r=32, alpha=64, target modules: q_proj, v_proj), ~9.4M trainable
parameters out of ~773M total
- Training data: 200 clips from Mozilla Common Voice 26.0 Sindhi (unvalidated split)
- Evaluation data: 324 clips from Mozilla Common Voice 26.0 Sindhi (validated split,
human-confirmed)
- Evaluation metric: Word Error Rate (jiwer)
Limitations
- Trained on a small amount of data (200 clips) due to compute constraints; a larger
training set would likely improve word-level accuracy further.
- The evaluation set, while human-validated, is relatively small (324 clips / Sindhi's
officially validated Common Voice data is limited).
- Not evaluated on speech outside the Common Voice domain (e.g. spontaneous conversational
speech, regional dialect variation).
Intended use
Research and experimentation with Sindhi ASR. Not intended for production or safety-critical
transcription use without further evaluation.