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| language: | |
| - ur | |
| license: cc-by-nc-4.0 | |
| pretty_name: "UrduTTS: 92-Hour Urdu Speech Corpus with Three-Way Transcriptions" | |
| size_categories: | |
| - 10K<n<100K | |
| source_datasets: | |
| - original | |
| task_categories: | |
| - text-to-speech | |
| - automatic-speech-recognition | |
| annotations_creators: | |
| - machine-generated | |
| language_creators: | |
| - found | |
| multilinguality: | |
| - monolingual | |
| tags: | |
| - urdu | |
| - speech | |
| - text-to-speech | |
| - tts | |
| - asr | |
| - low-resource | |
| - phonemes | |
| - ipa | |
| - romanization | |
| - south-asian-languages | |
| <div align="center"> | |
| # UrduTTS | |
| ### A Studio-Quality Urdu Speech Corpus with Urdu, Phonemized, and Romanized Transcriptions | |
| **91.9 hours · 57,873 utterances · 44.1 kHz · 3 aligned text representations** | |
| [](https://github.com/KAABSHAHID/UrduTTS) | |
| [](https://github.com/KAABSHAHID/UrduTTS) | |
| [](https://creativecommons.org/licenses/by-nc/4.0/) | |
| </div> | |
| --- | |
| ## Dataset Summary | |
| UrduTTS is the largest openly available Urdu text-to-speech corpus with **three aligned text | |
| representations** for every utterance: native **Urdu script**, **Phonemized** (IPA) text, and | |
| **Romanized** (Latin) text. | |
| Urdu is spoken by roughly 250 million people but is badly under-resourced in speech technology. | |
| Existing corpora are small, unreleased, or crowd-sourced with highly variable audio quality. | |
| UrduTTS provides 92 hours of clean, consistent read speech — and, critically, ships the phonemized | |
| layer that lets researchers move past the lossy Romanized transcriptions most Urdu TTS work has | |
| relied on. | |
| Released with our LREC 2026 paper, which uses it to show that **phonemized input outperforms | |
| romanized input on every metric measured**, for both VITS and Glow-TTS. | |
| ## Why three representations? | |
| Urdu is phonetically rich: aspirated/unaspirated contrasts (/k/ vs /kʰ/), retroflex consonants | |
| (ٹ، ڈ، ڑ), nasalized vowels, and pharyngeal consonants from Arabic and Persian. Romanized Urdu — | |
| the input format most prior neural Urdu TTS systems used — encodes none of this reliably and has no | |
| orthographic standard: خواب ("dream") is written *khawab*, *khwaab*, or *khwab* depending on the writer. | |
| | Representation | Field | Example | | |
| | :--- | :--- | :--- | | |
| | **Urdu** (Perso-Arabic) | `transcription` | جس کی مثال بندگانِ نفس میں ناممکن ہے | | |
| | **Phonemized** (IPA) | `phonemes` | `ɟɪs ki mɪsˈaːl bˌəndəɡˈaːn nˈafs mˈẽ nˈaːmʊmkˌɪn hɛ` | | |
| | **Romanized** (Latin) | `roman` | `JS KY MSAL BNDGAN NFS MYN NAMMKN HE` | | |
| *(English: "Whose example is impossible among the slaves of the self.")* | |
| The Romanized form drops the nasalized vowel in `mˈẽ`, the long vowels in `mɪsˈaːl`, and every stress | |
| mark. Quantifying that loss is what UrduTTS was built for. The clearest case: بڑی ("big") and بری | |
| ("bad") differ only by the retroflex ڑ, and both romanize to `BRY` — a contrast the model cannot | |
| learn because the input does not encode it. | |
| --- | |
| ## Quickstart | |
| ```python | |
| from datasets import load_dataset | |
| ds = load_dataset("XKaab/UrduTTS") | |
| sample = ds["train"][0] | |
| sample["audio"] # {'array': ndarray, 'sampling_rate': 44100, 'path': ...} | |
| sample["transcription"] # Urdu script | |
| sample["phonemes"] # IPA | |
| sample["roman"] # Romanized Latin | |
| ``` | |
| Stream it instead of downloading ~88 GB: | |
| ```python | |
| ds = load_dataset("XKaab/UrduTTS", split="train", streaming=True) | |
| sample = next(iter(ds)) | |
| ``` | |
| Resample to 22.05 kHz (the rate used for the paper's TTS training): | |
| ```python | |
| from datasets import Audio | |
| ds = ds.cast_column("audio", Audio(sampling_rate=22050)) | |
| ``` | |
| Play a sample in a notebook: | |
| ```python | |
| from IPython.display import Audio as Play | |
| s = ds["train"][0]["audio"] | |
| Play(s["array"], rate=s["sampling_rate"]) | |
| ``` | |
| --- | |
| ## Dataset Structure | |
| ### Fields | |
| | Field | Type | Description | | |
| | :--- | :--- | :--- | | |
| | `audio` | `Audio` | Mono 16-bit PCM WAV, 44.1 kHz | | |
| | `transcription` | `string` | Native Urdu script (Perso-Arabic, Nastaliq) | | |
| | `phonemes` | `string` | IPA phoneme sequence with stress marks, from eSpeak NG | | |
| | `roman` | `string` | Deterministic Latin transliteration | | |
| ### Splits | |
| | Split | Utterances | Duration | Share | | |
| | :--- | ---: | ---: | ---: | | |
| | `train` | 40,511 | 64.21 h | 70% | | |
| | `eval` | 11,575 | 18.41 h | 20% | | |
| | `test` | 5,787 | 9.24 h | 10% | | |
| | **Total** | **57,873** | **91.86 h** | | | |
| Utterance-level random split, `seed=42`, reproducible via | |
| [`data_pipeline/06_build_dataset.py`](https://github.com/KAABSHAHID/URDUTTS/blob/main/data_pipeline/06_build_dataset.py). | |
| ### Audio properties | |
| | Property | Value | | |
| | :--- | :--- | | |
| | Format | WAV, 16-bit PCM, mono | | |
| | Sampling rate | 44,100 Hz | | |
| | Mean clip length | 5.71 s | | |
| | Clip length range | 99.9% fall within 2–15 s (56 outliers, 0.19–41 s) | | |
| | Mean words / chars per utterance | 15.35 / 67.10 | | |
| | Speakers | 4 (all male) — see limitations | | |
| --- | |
| ## How the corpus was built | |
| Every stage is a runnable script in | |
| [the GitHub repository](https://github.com/KAABSHAHID/URDUTTS/tree/main/data_pipeline). | |
| 1. **Sourcing** — public-domain recordings (LibriVox, Internet Archive, Loyal Books), filtered for | |
| speaker consistency, pronunciation quality, and absence of background noise. | |
| 2. **Segmentation** — split on silence with pydub: a pause longer than **400 ms** below **-15 dBFS** | |
| marks a boundary; clips outside 2–15 s are rejected. | |
| 3. **Boundary synchronization** — 100 ms is trimmed from the end of each clip and prepended to the | |
| next within the same recording, so hard cuts do not sever word onsets. | |
| 4. **Transcription** — Urdu script via a Whisper-based pipeline (`faster-whisper`). | |
| 5. **Romanization** — deterministic grapheme-to-Latin transliteration with a fixed table. | |
| 6. **Phonemization** — IPA from **eSpeak NG** (`ur`), with stress marks preserved. | |
| --- | |
| ## Benchmark results | |
| VITS and Glow-TTS trained from scratch with Coqui TTS, once per text representation. Everything | |
| except the input representation is held constant. | |
| ### Objective (500 samples per system) | |
| | System | MCD Plain ↓ | MCD DTW ↓ | MCD DTW-SL ↓ | SNR (dB) ↑ | WER (%) ↓ | CER (%) ↓ | | |
| | :--- | ---: | ---: | ---: | ---: | ---: | ---: | | |
| | **VITS-Ph** | **17.00 ± 2.71** | **7.97 ± 1.66** | **9.35 ± 2.19** | **61.86** | **12.3** | **5.3** | | |
| | VITS-Rm | 17.53 ± 2.96 | 8.53 ± 1.74 | 9.98 ± 2.26 | 35.39 | 15.1 | 6.5 | | |
| | **Glow-Ph** | **17.71 ± 2.01** | **6.74 ± 0.98** | **7.42 ± 1.26** | **10.40** | **12.5** | **5.8** | | |
| | Glow-Rm | 18.83 ± 2.12 | 7.07 ± 1.07 | 7.86 ± 1.44 | 10.27 | 25.0 | 11.8 | | |
| ### Subjective (MOS, 40 native listeners, 95% CI) | |
| | System | MOS | | |
| | :--- | ---: | | |
| | Reference (ground truth) | 4.79 ± 0.12 | | |
| | **VITS-Phonemized** | **4.38 ± 0.24** | | |
| | VITS-Romanized | 3.86 ± 0.36 | | |
| | **GlowTTS-Phonemized** | **3.34 ± 0.28** | | |
| | GlowTTS-Romanized | 2.64 ± 0.31 | | |
| Phonemized input wins on every metric for both architectures: **+9.6% MOS for VITS** and **+26.5% | |
| MOS for Glow-TTS**. The clearest case is Glow-TTS intelligibility, where WER doubles under | |
| Romanization (25.0% vs 12.5%) — Romanized text cannot encode the retroflex and aspiration contrasts | |
| the model needs. | |
| --- | |
| ## Intended Uses | |
| **Direct use** — Urdu TTS and ASR, grapheme-to-phoneme and transliteration research, Urdu phonetics | |
| and prosody, and as a template for building resources in other under-resourced languages. | |
| **Out of scope** | |
| - **Commercial use of any kind** — the license is CC BY-NC 4.0 | |
| - Voice cloning or speaker impersonation of the corpus speakers | |
| - Generating deceptive synthetic speech attributed to a real person | |
| --- | |
| ## Limitations | |
| Please read before building on the corpus. | |
| - **All four speakers are male, and speaker labels are not included in this release.** Any voice | |
| trained on URDUTTS will be male, and per-speaker filtering or multi-speaker conditioning is not | |
| possible from the released fields alone. This is the corpus's most significant limitation. | |
| - **Transcriptions are ASR-generated, not hand-verified.** Urdu-script transcripts come from a | |
| Whisper-based pipeline and inherit its errors, which are non-trivial for Urdu. Because the | |
| Romanized and Phonemized layers are derived from those transcripts, an ASR error propagates to all | |
| three representations. | |
| - **9.8% of `roman` values contain residual Arabic diacritics** (5,669 rows — mostly U+0650 kasra and | |
| U+0670 superscript alef), e.g. `SFRِ HJ`. The transliteration table does not map combining marks, | |
| so they pass through. Strip them with `normalize_urdu()` from | |
| [`data_pipeline/urdu_romanizer.py`](https://github.com/KAABSHAHID/URDUTTS/blob/main/data_pipeline/urdu_romanizer.py), | |
| or filter with `re.sub(r'[^\x00-\x7F]', '', roman)`. | |
| - **Read speech in a formal register.** Sources are audiobook and literary recordings. | |
| Conversational Urdu, code-switching, and spontaneous speech are absent. | |
| - **Romanization is a fixed convention, not a standard.** It is deterministic and internally | |
| consistent, which is what makes the phonemized-vs-romanized comparison controlled. It deliberately | |
| reflects the lossiness of real Roman Urdu and is not a proposal for how Roman Urdu should be written. | |
| - **Phonemization inherits eSpeak NG's Urdu limitations.** Its Urdu front-end is rule-based and | |
| context-insensitive; short-vowel restoration in Perso-Arabic script is genuinely ambiguous | |
| (پر can be *par* or *pur*), so some phonemizations will be contextually wrong. | |
| ### Relation to the paper | |
| The paper's Table 2 reports **88.59 hours / 55,450 utterances at 22.05 kHz** with a per-speaker | |
| breakdown. This release is a slightly larger build — **91.86 hours / 57,873 utterances** — and | |
| stores audio at its native **44.1 kHz** rather than the 22.05 kHz used for TTS training; resample on | |
| load with `cast_column` as shown above. Speaker labels used for the paper's per-speaker table are | |
| not part of the released fields. | |
| --- | |
| ## Ethics | |
| All source audio came from publicly available, public-domain recordings. The dataset contains no | |
| personally identifiable information and was anonymized before release. Synthetic Urdu speech built | |
| from this corpus should be disclosed as synthetic wherever it is deployed, and should not be used to | |
| produce speech attributed to real, identifiable individuals. | |
| --- | |
| ## Citation | |
| ```bibtex | |
| @inproceedings{shahid-izharuddin-2026-urdutts, | |
| title = {A Benchmark Dataset and Comparative Evaluation of Phonemized and | |
| Romanized Urdu for Text-to-Speech}, | |
| author = {Shahid, M Kaab Bin and Izharuddin, Muhammed}, | |
| booktitle = {Proceedings of the Fifteenth Language Resources and Evaluation | |
| Conference (LREC 2026)}, | |
| year = {2026}, | |
| pages = {10982--10993}, | |
| publisher = {European Language Resources Association (ELRA)}, | |
| url = {https://github.com/KAABSHAHID/URDUTTS} | |
| } | |
| ``` | |
| ## License | |
| **CC BY-NC 4.0** — share and adapt for non-commercial purposes with attribution. | |
| See [creativecommons.org/licenses/by-nc/4.0](https://creativecommons.org/licenses/by-nc/4.0/). | |
| Code in the companion repository is MIT-licensed. | |
| Code, pipeline, and training recipes: **[github.com/KAABSHAHID/URDUTTS](https://github.com/KAABSHAHID/URDUTTS)** | |