Model Description
MediBeng Whisper Tiny FL is the federated learning (v3) release of Whisper Tiny for automatic speech translation of code-switched Bengali–English clinical conversations into English. Training uses FedProx across 4 simulated hospital clients with speaker-based non-IID data partitions — raw audio never leaves each client; only aggregated weight updates are shared.
This release is the best-performing FL checkpoint (FedProx speaker). It substantially outperforms centralised v2 under the same free-generation evaluation protocol.
What’s New in v3 (Federated Learning)
Table with columns: Area, v2 (centralised), v3 FL (this release)| Area | v2 (centralised) | v3 FL (this release) |
|---|
| Training paradigm | Single-server centralised fine-tuning | Federated learning (4 clients, 3 rounds) |
| Privacy | All training data pooled centrally | Raw audio stays on clients; only weight updates aggregated |
| Algorithms | Seq2SeqTrainer only | FedAvg + FedProx (this model: FedProx) |
| Client partitioning | N/A | Speaker non-IID (Male/Female hospital shards) |
| Non-IID handling | N/A | FedProx proximal term (μ = 0.01) reduces client drift |
| Local training | 500 central steps | 50 steps/round × 3 rounds × 4 clients = 600 client steps |
| Eval protocol | Free + forced generation (v2 discrepancy) | Free generation (canonical); free/forced consistent |
| Best test WER | 28.20% (centralised v2, free gen) | 3.12% (FedProx speaker, free gen) |
| Best test BLEU | 73.06 | 96.33 |
| Statistical testing | Bootstrap / McNemar vs baseline | Full suite for FL vs baseline and vs centralised v2 |
Federated architecture
┌─────────────────────────┐ │ FL Server (Aggregator) │ │ FedProx (μ = 0.01) │ └────────────┬────────────┘ │ broadcast global weights ┌─────────────────────┼─────────────────────┐ │ │ │ ┌──────▼──────┐ ┌──────▼──────┐ ┌──────▼──────┐ │ Client 0 │ │ Client 1 │ ... │ Client 3 │ │ Male shard │ │ Male shard │ │ Female shard│ │ 863 samples │ │ 863 samples │ │ 843 samples │ │ 50 local │ │ 50 local │ │ 50 local │ │ steps/round │ │ steps/round │ │ steps/round │ └──────┬──────┘ └──────┬──────┘ └──────┬──────┘ └─────────────────────┼─────────────────────┘ │ upload weight updates ┌────────────▼────────────┐ │ Weighted Aggregation │ └─────────────────────────┘
Training configuration
Table with columns: Parameter, Value| Parameter | Value |
|---|
| Base checkpoint | openai/whisper-tiny |
| Algorithm | FedProx (μ = 0.01) |
| Clients | 4 (speaker non-IID) |
| FL rounds | 3 |
| Local steps per round | 50 |
| Local learning rate | 1e-5 |
| Local batch size | 1 |
| Optimizer | AdamW |
| Total FL training time |
Usage
Install dependencies:
pip install transformers librosa torch datasets
Run inference (free generation — matches evaluation protocol):
from transformers import WhisperProcessor, WhisperForConditionalGenerationimport librosa MODEL_ID = "pr0mila-gh0sh/MediBeng-Whisper-Tiny-FL" processor = WhisperProcessor.from_pretrained(MODEL_ID)model = WhisperForConditionalGeneration.from_pretrained(MODEL_ID) # Free generation (canonical FL evaluation protocol)model.config.forced_decoder_ids = Nonemodel.generation_config.forced_decoder_ids = None audio, _ = librosa.load("path_to_audio.wav", sr=16000)input_features = processor(audio, sampling_rate=16000, return_tensors="pt").input_features predicted_ids = model.generate(input_features, max_length=225)translation = processor.batch_decode(predicted_ids, skip_special_tokens=True)[0] print("Translation:", translation)
Intended Use
For researchers and developers building privacy-preserving clinical AST systems:
- Multi-hospital deployment without centralising patient audio
- Federated fine-tuning research on code-switched clinical speech
- Bengali–English medical translation in regulated environments
Training Data
Fine-tuned via federated learning on the MediBeng training split, partitioned across 4 simulated clients:
Table with columns: Client, Partition, Samples| Client | Partition | Samples |
|---|
| 0 | Male speaker shard A | 863 |
| 1 | Male speaker shard B | 863 |
| 2 | Female speaker shard A | 843 |
| 3 | Female speaker shard B | 843 |
Test evaluation: held-out 960-sample HF test split (identical to v2).
Evaluation Results
Full test set (n = 960, free generation)
Table with columns: Setting, WER ↓, BLEU-4 ↑, chrF++ ↑| Setting | WER ↓ | BLEU-4 ↑ | chrF++ ↑ |
|---|
| Baseline (Whisper Tiny, unfine-tuned) | 81.12% | 32.20 | 45.12 |
| Centralised v2 | 28.20% | 73.06 | 79.28 |
| FL FedAvg IID | 6.16% | 93.66 | 94.38 |
| FL FedProx speaker (this model) | 3.12% | 96.33 | |
FedProx convergence (quick eval, n = 200 per round)
Table with columns: Round, Quick WER, Quick BLEU, Quick chrF++| Round | Quick WER | Quick BLEU | Quick chrF++ |
|---|
| 1 | 36.64% | 57.94 | 63.87 |
| 2 | 7.02% | 92.25 | 93.39 |
| 3 | 3.09% | 96.35 | 96.71 |
Statistical significance (FedProx vs baseline)
Table with columns: Test, Result| Test | Result |
|---|
| Bootstrap 95% CI (WER) | [2.41%, 3.46%] |
| Paired t-test | p = 6.95 × 10⁻¹⁶ |
| McNemar (≤5% WER) | 840/960 FL correct vs 0/960 baseline |
| Effect size (Cohen's d) | 0.27 |
Limitations
- Simulated clients — partitions use synthetic TTS speaker labels, not real multi-hospital data.
- 3 FL rounds — convergence may improve with more rounds.
- Centralised upper bound — comparison vs under-trained centralised v2; fully converged centralised baseline pending.
- Full weight transmission — ~156 MB per client per round; LoRA-FL not yet implemented.
- No differential privacy — formal ε–δ guarantees not yet added.
Ethical Considerations
- Federated learning reduces raw-data exposure but does not eliminate all privacy risks (model inversion, membership inference).
- Training data may reflect demographic biases; validate before clinical deployment.
- Human review required for all clinical translations.
Blog Post
MediBeng Whisper-Tiny: Translating Code-Switched Bengali-English Speech for Healthcare
Citation
Preprint on medRxiv.
@article{ghosh2025medibeng, title={MediBeng Whisper Tiny: A fine-tuned code-switched Bengali-English translator for clinical applications}, author={Ghosh, Promila and Talukder, Sunipun}, journal={medRxiv}, year={2025}, doi={https://doi.org/10.1101/2025.04.25.25326406}, url={https://www.medrxiv.org/content/10.1101/2025.04.25.25326406v2}}