---
license: mit
language:
  - en
  - de
  - fr
  - es
task_categories:
  - text-to-speech
tags:
  - g2p
  - phonemization
  - ipa
  - pronunciation
  - tts
  - piper
pretty_name: G2P Pronunciation Dictionaries
size_categories:
  - 1M<n<10M
---

# G2P Pronunciation Dictionaries for CrispASR

IPA pronunciation dictionaries for text-to-phoneme conversion in TTS
backends (piper, kokoro, melotts). Auto-downloaded by CrispASR on first use.

## Pre-generated IPA Dictionaries (primary — piper-compatible)

Pre-generated IPA transcriptions matching the phoneme inventory of
piper TTS models. These are factual phonetic data — word-to-IPA mappings
generated by processing vocabulary lists through a phonemization engine.

| File | Language | Entries | Size | Source vocabulary |
|------|----------|---------|------|-------------------|
| `espeak_en_us.tsv` | English (US) | 126K | 3 MB | [CMUdict](https://github.com/cmusphinx/cmudict) (BSD) |
| `espeak_de.tsv` | German | 667K | 23 MB | [open-dict-data](https://github.com/open-dict-data/ipa-dict) single words |
| `espeak_fr.tsv` | French | 257K | 6.6 MB | [OLaPh](https://github.com/iisys-hof/olaph) FR (MIT) |
| `espeak_es.tsv` | Spanish | 600K | 18 MB | [OLaPh](https://github.com/iisys-hof/olaph) ES (MIT) |

**Format:** `word\t/IPA/` (tab-separated, IPA in slashes, one entry per line)

**Benchmark:** 99.5% exact match (EN) / 100% (DE) against piper model
ground truth on a 382-word test set.

## CMUdict (English ARPAbet — fallback)

| File | Language | Entries | Source | License |
|------|----------|---------|--------|---------|
| `cmudict.dict` | English | 126K | [CMU Sphinx](https://github.com/cmusphinx/cmudict) | BSD |

**Format:** `WORD PH1 PH2 PH3` (space-separated ARPAbet phonemes).
CrispASR converts ARPAbet to IPA at runtime (76% piper match rate).

## OLaPh Dictionaries (MIT — multilingual fallback)

| File | Language | Entries | License |
|------|----------|---------|---------|
| `olaph_en_us.txt` | English (US) | 508K | MIT |
| `olaph_de.txt` | German | 1.12M | MIT |
| `olaph_fr.txt` | French | 259K | MIT |
| `olaph_es.txt` | Spanish | 600K | MIT |

**Format:** `word\t/IPA/` (same as pre-generated dicts).
OLaPh uses British English IPA conventions (ɐ for -er, ɒ for LOT);
the pre-generated dicts above use American conventions matching piper models.

**Source:** [iisys-hof/olaph](https://github.com/iisys-hof/olaph) —
Becker et al., "OLaPh: Optimal Language Phonemizer",
[arXiv:2509.20086](https://arxiv.org/abs/2509.20086), MIT license.

## Usage in CrispASR

Dictionaries are auto-downloaded to `~/.cache/crispasr/` on first TTS use:

```bash
# Default: uses pre-generated IPA dicts (piper-compatible)
crispasr --backend piper -m auto --auto-download --tts "Hello world" --tts-output out.wav

# Select dictionary source explicitly
crispasr --backend piper --g2p-dict cmudict --tts "Hello world" --tts-output out.wav
crispasr --backend piper --g2p-dict olaph --tts "Hello world" --tts-output out.wav

# Use a custom dictionary file
crispasr --backend piper --g2p-dict /path/to/my/dict.txt --tts "Hello world" --tts-output out.wav
```

Override per-language paths with environment variables:
- `CRISPASR_CMUDICT_PATH` — English CMUdict file
- `CRISPASR_DE_DICT_PATH` / `CRISPASR_FR_DICT_PATH` / `CRISPASR_ES_DICT_PATH`

## Phonemization Cascade

CrispASR tries pronunciation sources in priority order:

1. **Pre-generated IPA dict** (99.5% piper match) — auto-downloaded
2. **CMUdict + ARPAbet→IPA** (EN, 76% match) / **OLaPh** (DE/FR/ES)
3. **LTS rules** (letter-to-sound, always available, zero dependencies)
4. **espeak-ng via dlopen** (loaded at runtime if installed on system)
5. **espeak-ng via popen** (subprocess fallback)

## Attribution

- **CMUdict**: Carnegie Mellon University, BSD license.
  https://github.com/cmusphinx/cmudict
- **OLaPh**: Becker, M. et al. (2025). "OLaPh: Optimal Language Phonemizer."
  arXiv:2509.20086. MIT license. https://github.com/iisys-hof/olaph
- **open-dict-data**: CC-BY-SA 3.0 (Wiktionary-sourced).
  https://github.com/open-dict-data/ipa-dict

## License

This dataset is released under the **MIT license**.

- Pre-generated IPA dicts: factual phonetic data (word→IPA mappings)
- CMUdict: BSD license
- OLaPh dicts: MIT license
- open-dict-data vocabulary (used as word source for DE): CC-BY-SA 3.0