Whisper-Small Dutch - Full Synthetic Data (Unfiltered)
This model is a fine-tuned version of openai/whisper-small for Dutch automatic speech recognition (ASR). It was trained on Common Voice 17.0 Dutch combined with all synthetic speech data without quality filtering, representing the maximum data augmentation approach.
Introduction
Purpose
This model uses all available synthetic data without WAVe quality filtering to evaluate the impact of maximum data augmentation. It achieves strong performance (10.91% Test WER) but requires significantly more training steps than filtered approaches, demonstrating the quality-vs-quantity tradeoff in synthetic data augmentation.
How the Data Was Created
The training data combines real speech from Common Voice 17.0 with the complete synthetic dataset:
Transcript Generation: We used GPT-4o-mini to generate Dutch transcripts that match the word count distribution observed in Common Voice, ensuring realistic utterance lengths and diverse linguistic content.
Speech Synthesis: Each transcript was converted to audio using OpenAI's TTS-1 model with 9 different voice variants (alloy, ash, coral, echo, fable, nova, onyx, sage, shimmer), producing 34,898 synthetic samples.
No Quality Filtering: Unlike other models in this series, no WAVe filtering was applied. All 34,898 synthetic samples were used, including those with potential synthesis defects.
How the Model Was Created
The model was fine-tuned from openai/whisper-small using the Hugging Face Transformers library:
Mixed Training: Combined 34,952 real speech samples from Common Voice 17.0 Dutch with all 34,898 synthetic samples (69,850 total).
Optimization: Trained for 5 epochs with a learning rate of 1e-5, global batch size of 256, and BF16 precision on an NVIDIA H200 GPU.
Checkpoint Selection: The best checkpoint was selected based on validation loss, occurring at step 800 with a validation loss of 0.1484.
This approach achieves 2.0% relative improvement over the baseline (10.91% vs 11.13% Test WER) but requires 100% more training steps than training on Common Voice only.
Model Details
Property
Value
Base Model
openai/whisper-small
Language
Dutch (nl)
Task
Automatic Speech Recognition (transcribe)
Parameters
244M
Training Data
Common Voice 17.0 + All Synthetic (Unfiltered)
Total Training Samples
69,850
Sampling Rate
16kHz
Evaluation Results
This Model (whisper-small-cv-fully-synthetic-nl)
Metric
Value
Validation Loss
0.1484
Validation WER
8.64%
Test WER (Common Voice)
10.91%
Test WER (MLS)
30.06%
Best Checkpoint
Step 800
Max Training Steps
1,365
Comparison with Other Training Configurations (Whisper-Small Dutch)
Training Data
Max Steps
Val Loss
Val WER
Test WER (CV)
Test WER (MLS)
Common Voice Only
680
0.1491
8.73%
11.13%
30.71%
High-Quality Filtered + CV
890
0.1493
8.76%
11.00%
29.91%
Mid-High Quality Filtered + CV
1,270
0.1484
8.73%
10.86%
30.04%
All Synthetic + CV (Unfiltered)
1,365
0.1484
8.64%
10.91%
30.06%
Key Performance Highlights
Best Validation WER (8.64%) among all Whisper-Small Dutch configurations
2.0% relative improvement on Common Voice test set vs baseline (10.91% vs 11.13%)
2.1% relative improvement on MLS benchmark vs baseline (30.06% vs 30.71%)
Tradeoff: Requires 1,365 steps vs 890 for high-quality filtered (53% more compute)
This model demonstrates the tradeoff between data quantity and quality for Whisper-Small:
Approach
Synthetic Samples
Training Steps
Test WER (CV)
Efficiency
High-Quality (q≥0.8)
10,555
890
11.00%
Best
Mid-High (q≥0.5)
30,182
1,270
10.86%
Good
Unfiltered (this model)
34,898
1,365
10.91%
Lowest
Key insight: The unfiltered approach performs slightly worse than mid-high filtering (10.91% vs 10.86%) despite using more data and requiring 7.5% more training steps. This suggests that including low-quality synthetic samples can introduce noise that degrades performance for Whisper-Small.
Limitations
Training efficiency: Requires most compute among all configurations
Noisy training signal: Includes low-quality synthetic samples (13.5% with q < 0.5)
Diminishing returns: More data doesn't always mean better performance
Domain specificity: Optimized for general Dutch; may underperform on technical domains
Dialect coverage: Performance may vary across Dutch regional variants
Citation
bibtex
1@article{perezhohin2024enhancing,
2 title={Enhancing Automatic Speech Recognition: Effects of Semantic Audio Filtering on Models Performance},
3 author={Perezhohin, Yuriy and Santos, Tiago and Costa, Victor and Peres, Fernando and Castelli, Mauro},
4 journal={IEEE Access},
5 year={2024},
6 publisher={IEEE}
7}