Multilingual Text to Speech
Generate AI speech in Chinese, English, Japanese, Spanish, and Arabic with one Index TTS 2.5 workflow.
Index TTS 2.5: Multilingual Text to Speech & Voice Cloning
Index TTS 2.5 supports zero-shot voice cloning, cross-language voice generation, emotion control, speaking-speed adjustment, and pronunciation guidance in one online workflow.
- 5 Supported Languages
- Zero-Shot Voice Cloning
- Cross-Language Generation
- Emotion, Speed & Pronunciation Control
Powered by Index TTS Models
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Reference voice · Required Upload a clean 3–10 second recording of an authorized voice.
Advanced settings
Emotional audio
Audio Examples
Listen to official Index TTS examples before generating your own.
English · Sad
“I feel like I'm lost in the darkness and can't find a way out anymore.”
What Is Index TTS 2.5?
Index TTS 2.5 is a multilingual AI text-to-speech model for zero-shot voice cloning, expressive speech generation, and cross-language voice workflows. With a short reference recording, you can generate new speech that follows the voice characteristics of the reference while using your target text as the spoken content.
Compared with earlier Index TTS generations, Index TTS 2.5 expands multilingual support across Chinese, English, Japanese, Spanish, and Arabic, while adding more flexible controls for speaking speed, pronunciation, and expressive delivery.
These capabilities make Index TTS 2.5 well suited for multilingual narration, localization, dubbing, education, games, marketing, and other workflows that need consistent voice generation across languages and scripts.
Key Features of Index TTS 2.5
Index TTS 2.5 combines multilingual text-to-speech, zero-shot voice cloning, cross-language generation, expressive delivery, and speech controls in one workflow.
Zero-Shot Voice Cloning
Use a short reference recording to guide the generated voice without training a separate custom speaker model.
Cross-Language Voice Generation
Use a reference voice in one supported language to generate speech in another while retaining key voice characteristics.
Emotion Control
Adjust the emotional delivery of generated speech while keeping the reference voice characteristics consistent.
Speaking-Speed Control
Control speaking pace for narration, promotional content, tutorials, learning materials, and other voice workflows.
Pronunciation Guidance
Guide pronunciation for names, technical terms, uncommon words, homographs, and other context-sensitive text.
Supported Languages in Index TTS 2.5
Index TTS 2.5 supports Chinese, English, Japanese, Spanish, and Arabic, enabling multilingual text-to-speech and cross-language voice generation within one workflow.
Use the same authorized reference voice across supported languages for multilingual narration, localization, dialogue, product content, and other voice workflows.
English
Generate natural English speech with expressive controls and CMU phoneme-based pronunciation guidance.
Español
Spanish
Generate Spanish speech for multilingual narration, localization, dialogue, and other cross-language workflows.
العربية
Arabic
Generate Arabic speech for multilingual and cross-language voice workflows with supported expressive controls.
中文
Chinese
Generate Chinese speech with support for expressive delivery and Pinyin-based pronunciation guidance.
日本語
Japanese
Generate Japanese speech with expressive delivery and Kana-based pronunciation guidance.
Cross-Language Voice Generation
Index TTS 2.5 can use reference audio in one supported language to generate speech in another, helping maintain consistent voice characteristics across multilingual content.
This is useful for localized narration, character dialogue, product videos, learning content, and international media where the same voice needs to appear across multiple languages.
Tip: Review pronunciation, names, numbers, translations, and accent quality with a fluent speaker before publishing multilingual audio.
Index TTS 2 vs. Index TTS 2.5: What’s Different?
Index TTS 2.5 builds on Index TTS 2 with five-language support, faster inference, expanded pronunciation guidance, and direct speaking-speed control, while preserving zero-shot voice cloning, cross-language generation, and expressive speech features.
Zero-Shot Voice Cloning
Index TTS 2.5
Retains zero-shot voice cloning while extending the workflow across more languages and production controls.
Index TTS 2
Supports zero-shot voice cloning from reference audio.
Emotion Control
Index TTS 2.5
Retains emotion control while combining it with multilingual generation, speed adjustment, and expanded pronunciation guidance.
Index TTS 2
Built around highly expressive speech synthesis with emotion control through multiple input methods.
Language Support
Index TTS 2.5
Explicitly supports Chinese, English, Japanese, Spanish, and Arabic in the current release.
Index TTS 2
Earlier generation with cross-language capabilities.
Cross-Language Generation
Index TTS 2.5
Retains cross-language generation and extends it across the broader five-language workflow.
Index TTS 2
Supports cross-language speech generation.
Pronunciation Guidance
Index TTS 2.5
Expands pronunciation guidance to Chinese Pinyin, English CMU phonemes, and Japanese Kana.
Index TTS 2
Supports Chinese Pinyin-based pronunciation control.
Speaking Speed and Timing
Index TTS 2.5
Provides direct generation-time speed control through duration_factor, with a documented range of 0.5–2.0× audio duration.
Index TTS 2
Introduced precise synthesis-duration control, although the official release notes state that the functionality was not enabled in that release.
Inference Speed
Index TTS 2.5
The official project reports faster inference than Index TTS 2, with benchmark results published for RTX 4090 testing.
Index TTS 2
Earlier-generation inference baseline.
Which Index TTS Model Fits Your Workflow?
Use Index TTS 2.5 when your project benefits from five-language support, cross-language generation, expanded pronunciation guidance, speaking-speed control, or faster inference.
Read the Index TTS 2.5 Review →Use Index TTS 2 when you specifically want to explore its expressive-speech and emotion-control workflow.
Explore Index TTS 2 →How to Use Index TTS 2.5
Generate multilingual AI speech with Index TTS 2.5 in a few simple steps. Start with your text and an authorized reference recording, adjust the available speech controls, then generate and review the result.
Enter Your Text
Add the script, narration, dialogue, or other text you want Index TTS 2.5 to generate as speech. Choose a supported language and review names or terms that may need pronunciation guidance.
Upload a Reference Voice
Upload a short, clean recording from a voice you own or have permission to use. For better results, use clear speech from a single speaker with minimal background noise or music.
Adjust Voice Settings
Configure the controls available for your workflow, such as emotion, speaking speed, and pronunciation guidance. Settings may vary depending on the language and generation mode.
Generate and Preview
Generate the speech and listen to the result. Check voice similarity, pronunciation, pacing, and expression, then refine your text or settings and generate again if needed.
Want a more detailed walkthrough? Read How to Use Index TTS →
Index TTS 2.5 Use Cases
Use Index TTS 2.5 for multilingual voice generation, zero-shot voice cloning, and projects that need more control over expression, pacing, and pronunciation than a basic text-to-speech workflow.
Video Localization
Create multilingual voiceovers for product videos, tutorials, explainers, and regional content using the same authorized reference voice across supported languages.
Audiobooks and Narration
Generate long-form narration with a consistent reference voice, adjustable speaking speed, and pronunciation guidance for names, terms, and complex passages.
Education and Training
Create lessons, training materials, explainers, and instructional audio for multilingual audiences with flexible pacing and speech controls.
Games and Character Dialogue
Generate multilingual character dialogue and experiment with different emotional delivery styles using an authorized reference voice.
Marketing and Advertising
Create localized voiceovers for campaigns, product stories, social media, promotional videos, and other multilingual marketing content.
Product Demos and Onboarding
Add generated speech to product walkthroughs, demos, onboarding flows, presentations, and multilingual product experiences.
Index TTS 2.5 FAQ
Get answers about Index TTS 2.5, multilingual text-to-speech, zero-shot voice cloning, supported languages, pronunciation guidance, speaking-speed control, and online generation.
Try Index TTS 2.5 Online
Generate multilingual AI speech with a short authorized reference recording. Adjust language, emotion, speaking speed, and pronunciation, then preview the result before using it in your project.
Use only voices you own or have permission to use.