Tachelhiyt-Darija: a parallel speech corpus for two underrepresented languages
Paper · 2025 · Noureddine Atouf, Elsayed Issa and Said Ouzbayr
Summary
Speech technology still serves Amazigh and Moroccan Arabic (Darija) poorly, mainly because there is so little recorded, transcribed data for them. The authors build what they describe as the first parallel speech corpus pairing Tachelhiyt, an Amazigh variety, with Darija. They wrote or collected Darija sentences, partly from a Peace Corps textbook. Two native speakers then translated them into Tachelhiyt, and both sides were written in Arabic script rather than Tifinagh or phonetic notation, to make them easier to read. Native speakers recorded the sentences at home on their own devices. The recordings were split automatically, checked by hand and released on Hugging Face with speaker and gender metadata. As a baseline, the authors ran Whisper without any adaptation, and the error rates were very high, above 100% WER for Tachelhiyt. After fine-tuning Whisper small separately for each language, errors fell to single-digit WER. The work matters because it supplies a sentence-level, aligned resource for two neglected North African languages. It also shows that off-the-shelf multilingual ASR does little for them until it is adapted to local data.
Key points
- The corpus has 2,772 segments recorded by 24 Tachelhiyt and 11 Darija speakers (35 in total, 60% female, mostly under 19). It contains 71.68 min of Tachelhiyt audio (average segment 3.11 s) and 61.84 min of Darija (average 2.68 s). It is published as
NoureddineMOR/tachelhiyt-darija. - Audio was converted to mono 16 kHz 16-bit PCM WAV with FFmpeg. For each language there is a CSV of file name and transcript, plus an eight-column parallel metadata file with audio, transcript, speaker and gender for each side.
- Zero-shot Whisper was tested on 300 samples (WER/CER):
- Tachelhiyt: small 127.09/80.85, large-v3 145.54/85.86, so the larger model did worse.
- Darija: small 89.72/60.47, large-v3 76.08/34.44.
- Fine-tuning Whisper small used batch 16, learning rate 1e-5 and 1000 steps (about 15 epochs) on one A100. It reached 7.45/3.25 on Tachelhiyt and 4.26/1.38 on Darija.
- The limitations the authors list are recording-quality variation from home devices and the small, parallel nature of the data. They plan an expanded corpus covering all three Tamazight varieties.
Interesting ideas
- I1. Pivot-language corpus building: sentences are written first in the better-resourced variety, then translated by native speakers into the scarcer one, so alignment exists from the start without needing scarce source texts.
- I2. Built-in segment boundaries: recorders left a fixed five-second pause between items, so splitting could be automatic, and a person only had to check the alignment afterwards.
- I3. Scaling as a test condition, not an assumption: comparing two model sizes zero-shot showed the bigger Whisper getting worse on the unseen language while improving on the other one.
- I4. One shared script for both sides: writing both languages in Arabic script makes the pair easier to read and compare, instead of mixing Tifinagh and phonetic notations.
- I5. Parallel metadata with speaker and gender fields: this lets users filter and break down results by subgroup and by language side for each aligned item.
For Mova
How these ideas could serve Mova, our small open language model — its files, stages and tests:
- I1 (back): build paired English source/target sets this way for testing translation through the meta-world, with meaning fixed before the second wording is produced.
- I2 (learn): when collecting silver data, add explicit delimiters or IDs at creation time, so alignment is checked rather than guessed.
- I3 (tree): compare gparse against the perceptron parser on out-of-domain or dialectal text, and do not assume the larger model wins everywhere.
- I4 (tokens): map spelling and dialect variants into one canonical orthography before tagging and lemmatization, so the same word is not split across forms.
- I5 (answer): attach source, variant and paraphrase-pair IDs to test items, so errors on school tests or fable QA can be sliced by subgroup.
Fields, topics and concepts
📚 Shelves 2The field of science this work belongs to (OpenAlex fields).Computer Science · 18,614 worksArtificial Intelligence · 17,965 works
🧭 Topics 1Research subjects and languages the work is about.Speech & spoken language · 519 works
Cite
Cite as Noureddine Atouf, Elsayed Issa and Said Ouzbayr. 2025. Tachelhiyt-Darija: a parallel speech corpus for two underrepresented languages. Proceedings of the 8th International Conference on Natural Language and Speech Processing (ICNLSP-2025).
@inproceedings{atouf2025tachelhiyt,
title = {{Tachelhiyt-Darija: a parallel speech corpus for two underrepresented languages}},
author = {Noureddine Atouf, Elsayed Issa and Said Ouzbayr},
booktitle = {Proceedings of the 8th International Conference on Natural Language and Speech Processing (ICNLSP-2025)},
year = {2025},
url = {https://aclanthology.org/2025.icnlsp-1.37/}
}References
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