JOY — Greek Piper TTS Voice (el_GR-joy-medium)
JOY is a high-quality Greek Piper TTS voice trained entirely on human recordings by a native Greek speaker with formal academic training in linguistics and philology.
It was created to fill the gap in open-source Greek TTS — all existing community voices were trained on synthetic or low-quality data, resulting in robotic, mispronounced output unsuitable for educational or assistive applications.
Voice Overview
| Field | Value |
|---|---|
| Voice name | JOY |
| Greek name | Χαρά (Chara) |
| Language | Greek (el_GR) |
| Quality | medium |
| Architecture | Piper VITS |
| Sample rate | 22050 Hz |
| Speaker | Chara Kaltsou |
| License | CC BY-NC 4.0 |
Speaker
Chara Kaltsou BA, Department of German Language and Philology, Aristotle University of Thessaloniki (AUTH) MA, Hellenic Open University of Patras (HOU) Native Greek speaker
Training
| Parameter | Value |
|---|---|
| Training framework | piper-train (official) |
| Base checkpoint | rhasspy/piper-checkpoints el_GR rapunzelina medium |
| Dataset size | 3,216 utterances (human recordings) |
| Dataset format | LJSpeech (22050 Hz WAV + metadata.csv) |
| Quality | medium (VITS) |
| Recording environment | Quiet room, USB condenser microphone |
Usage
Download both files and point Piper at the .onnx:
echo "Καλημέρα, πώς είσαι;" | piper \
--model el_GR-joy-medium.onnx \
--output_file output.wav
Or from Python via the Piper HTTP server, or any llama.cpp / llama-server build with Piper TTS support.
Files
| File | Description |
|---|---|
el_GR-joy-medium.onnx |
Voice model (63 MB) |
el_GR-joy-medium.onnx.json |
Config (inference params, phoneme map) |
License: CC BY-NC 4.0
Creative Commons Attribution-NonCommercial 4.0 International
You are free to share and adapt this voice for non-commercial purposes with attribution.
Required attribution: "JOY Greek voice — Gemma4GR project, CC BY-NC 4.0" Link: https://github.com/Efs-O/Gemma4GR
Commercial use requires explicit written permission: amandoulou@yahoo.gr
Full license: https://creativecommons.org/licenses/by-nc/4.0/legalcode
Citation
@misc{gemma4gr-joy-voice-2026,
title = {JOY: A High-Quality Greek Piper TTS Voice},
author = {Kaltsou, Chara},
year = {2026},
url = {https://huggingface.co/Efso/joy-greek-tts},
note = {CC BY-NC 4.0. Speaker: Chara Kaltsou, BA AUTH, MA HOU}
}