Towards stable AI systems for Evaluating Arabic Pronunciations
Summary
Self-supervised speech models such as wav2vec 2.0 transcribe words and sentences well but do poorly when the input is a single spoken Arabic letter. A lone letter lasts only a fraction of a second, has no neighbouring sounds that shape it, and carries no lexical context. Emphatic and pharyngeal consonants make the task harder still. The authors built "Horouf", a corpus of about ten thousand recordings of diacritised isolated letters, collected through their own web and Android apps from native and non-native speakers. Off-the-shelf wav2vec 2.0 reaches roughly 35% accuracy on it. A small MLP trained on wav2vec embeddings raises this to about 65%. That MLP is fragile: a tiny amplitude perturbation (ϵ = 0.05) pushes it back to about 32%. PGD-based adversarial training limits the loss under noise to about 9 points and keeps clean accuracy. The work matters for pronunciation tutoring, speech therapy and Tajweed checking, where each individual letter has to be judged.
Key points
- Each label is a letter–diacritic pair (fatha /a/, kasra /i/, damma /u/, sokoon), which gives 112 classes in total.
- The Horouf dataset has about 10k recordings with speaker metadata (gender, age, nativeness, continent). Annotation was done by experts, and the data and code are available on request.
- Reported accuracies:
- pretrained wav2vec 2.0: about 35%;
- MLP on wav2vec embeddings: about 65% on clean audio;
- the same MLP at ϵ = 0.05: about 32%.
- Under PGD attacks of growing strength (ϵ up to 0.15), the vanilla MLP nearly collapses. The adversarially trained MLP with the same architecture declines only modestly.
- Planned future work: combine a grapheme-level segmenter with the letter classifier to score each letter inside whole words. Example: telling "abi" apart from the learner error "api".
Interesting ideas
- I1. Testing a strong model on minimal units with all context removed exposes weaknesses that context normally hides. — For Mova (tokens): Run the tagger and lemmatiser on isolated words or very short fragments to see which decisions depend on context and which come from the word itself.
- I2. A curve of accuracy against perturbation strength (clean, then increasing ϵ) is a more honest measure than a single clean score. — For Mova (learn): Plot parser and frame accuracy against controlled text noise levels (typos, casing, punctuation loss) and report this next to the negative controls.
- I3. Adversarial training feeds the model the worst-case input inside a bounded neighbourhood, so stability is learned rather than hoped for. — For Mova (tree): When training the perceptron parser or gparse, add the token or embedding perturbations that most hurt the current model, with a strict bound on how much they change the input.
- I4. A light classifier head on frozen pretrained embeddings nearly doubled accuracy over the end-to-end model on a niche task. — For Mova (tree): Small probing heads on frozen gparse representations could cover rare UD relations or dialect conversions without retraining the whole transformer.
- I5. Segment the input, give each unit its own confidence, then combine them into an overall score, so feedback points at the exact faulty piece. — For Mova (answer): When grading student answers or maths solutions, score each step or clause separately and show which one failed instead of returning a single pass/fail verdict.
Cite
@misc{zaatiti2025stable,
title = {{Towards stable AI systems for Evaluating Arabic Pronunciations}},
author = {Zaatiti, Hadi and Hajri, Hatem and Abdullah, Osama and Masmoudi, Nader},
year = {2025},
doi = {10.48550/arxiv.2508.19587},
eprint = {2508.19587},
archivePrefix = {arXiv},
url = {https://doi.org/10.48550/arxiv.2508.19587}
}References
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