Whisper-Tiny Portuguese - Mid-High Quality Filtered Synthetic Data

This model is a fine-tuned version of openai/whisper-tiny for Portuguese automatic speech recognition (ASR). It was trained on Common Voice 17.0 Portuguese combined with WAVe-filtered synthetic speech data using a balanced quality threshold (q ≥ 0.5), including both high-quality and medium-quality samples.

Purpose

This model tests whether the mid-high quality threshold (q ≥ 0.5) that works optimally for Large-v3 models can benefit Tiny architectures. The results reveal a critical architectural finding:

Key Finding: The balanced threshold that produces the best cross-domain results for Large-v3 actually hurts Tiny performance, demonstrating that optimal filtering thresholds are architecture-dependent.

While Large-v3 achieves its best cross-domain performance with this threshold, Tiny shows degraded MLS performance despite marginal in-domain improvement.

Model Details

Evaluation Results

This Model (whisper-tiny-mixed-pt)

Comparison with Other Training Configurations (Whisper-Tiny Portuguese)

Key Performance Characteristics

• Marginal in-domain gain: 30.11% vs 30.72% baseline (+2.0% relative)
• Worse cross-domain: 47.25% MLS WER vs 45.83% baseline (-3.1%)
• Largest filtered dataset: 19,181 synthetic samples used (87.3%)
• Most steps among filtered: 805 max steps for suboptimal results
• Demonstrates threshold dependency: What works for Large-v3 doesn't work for Tiny

Why Mid-High Filtering Hurts Tiny Models

The paper provides insight into this phenomenon:

"Compact models, with fewer parameters, struggle to disentangle the subtle acoustic differences between natural and synthetic speech. Unlike the Large-V3 model, which can exploit its deeper representational hierarchy to extract meaningful patterns, smaller models become overwhelmed by increased acoustic variability."

For Tiny models:

• Adding medium-quality synthetic samples (0.5 ≤ q < 0.8) introduces noise the model cannot filter
• The larger dataset size (41k vs 22k) creates more confusion rather than benefit
• Cross-domain performance actually degrades (47.25% vs 45.83%)
• Only strict high-quality filtering (q ≥ 0.8) provides improvement

Tiny vs Large: Same Threshold, Opposite Results

This stark contrast demonstrates that optimal data augmentation strategies are architecture-specific.

Training Data

Dataset Composition

WAVe Quality Distribution (Portuguese Synthetic Data)

This threshold retains 87.3% of the synthetic dataset—too much variability for Tiny's limited capacity.

Training Procedure

Hyperparameters

Training Infrastructure

• GPU: NVIDIA H200 (140GB VRAM)
• Operating System: Ubuntu 22.04
• Framework: Hugging Face Transformers

Usage

Transcription Pipeline

from transformers import pipeline

transcriber = pipeline(
    "automatic-speech-recognition",
    model="yuriyvnv/whisper-tiny-mixed-pt",
    device="cuda"
)

result = transcriber("path/to/portuguese_audio.wav")
print(result["text"])

Direct Model Usage

from transformers import WhisperProcessor, WhisperForConditionalGeneration
import librosa

processor = WhisperProcessor.from_pretrained("yuriyvnv/whisper-tiny-mixed-pt")
model = WhisperForConditionalGeneration.from_pretrained("yuriyvnv/whisper-tiny-mixed-pt")
model.to("cuda")

audio, sr = librosa.load("path/to/portuguese_audio.wav", sr=16000)
input_features = processor(audio, sampling_rate=16000, return_tensors="pt").input_features.to("cuda")

predicted_ids = model.generate(input_features)
transcription = processor.batch_decode(predicted_ids, skip_special_tokens=True)[0]
print(transcription)

Specifying Language

model.generation_config.language = "pt"
model.generation_config.task = "transcribe"

When to Use This Model

Generally not recommended for production. This model is primarily useful for:

• Research purposes: Understanding how filtering thresholds interact with model capacity
• Ablation studies: Complete picture of threshold effects across architectures
• Demonstrating architecture-dependency: Showing that optimal strategies differ by model size

For production use:

• whisper-tiny-high-mixed-pt: Best Tiny (29.33% WER)
• whisper-tiny-cv-only-pt: Simpler, nearly as good
• whisper-large-v3-mixed-pt: Best cross-domain if resources permit

Research Implications

This model provides evidence for a key finding:

Filtering thresholds that optimize large models may harm smaller ones.

For practitioners:

1. Don't assume threshold transferability: Optimal q threshold depends on model size
2. Tiny/Small need stricter filtering: Only q ≥ 0.8 helps; q ≥ 0.5 hurts
3. Large models are more robust: Can leverage medium-quality data effectively
4. Test before deploying: Validate augmentation strategies on target architecture

Limitations

• Worse MLS than baseline: 47.25% vs 45.83% (degraded cross-domain)
• Marginal in-domain improvement: Not worth the additional complexity
• Wasted compute: 87% more training steps for mixed results
• Domain specificity: Optimized for general Portuguese

Citation

This model is part of research on WAVe (Word-Aligned Verification) for synthetic speech quality assessment. While the WAVe methodology paper is currently under review, please cite our previous work that motivated this research:

@article{perezhohin2024enhancing,
  title={Enhancing Automatic Speech Recognition: Effects of Semantic Audio Filtering on Models Performance},
  author={Perezhohin, Yuriy and Santos, Tiago and Costa, Victor and Peres, Fernando and Castelli, Mauro},
  journal={IEEE Access},
  year={2024},
  publisher={IEEE}
}

@article{perezhohin2026wave,
  title={WAVe: Word-aligned verification of synthetic speech for ASR},
  author={Perezhohin, Yuriy and Castelli, Mauro},
  journal={Information Sciences},
  pages={123591},
  year={2026},
  publisher={Elsevier}
}

References

• Base Model: openai/whisper-tiny
• Training Data (Real): mozilla-foundation/common_voice_17_0
• Training Data (Synthetic): yuriyvnv/synthetic_transcript_pt
• Whisper Paper: Robust Speech Recognition via Large-Scale Weak Supervision
• Motivating Research: Enhancing ASR with Semantic Audio Filtering (IEEE Access 2024)

License

Apache 2.0