---
title: Create your own voice for Gemini 3.8 TTS
link: https://www.philschmid.de/gemini-3-8-tts
source: philschmid-de
published: 2026-09-24T00:00:00Z
updated: 2026-09-24T00:00:00Z
first_seen: 2026-09-27T19:29:15.293681927Z
summary: Gemini 3.8 Flash TTS lets you replicate your own voice or design one from a sentence, then direct delivery line by line.
content: extracted
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---

[Gemini 3.8 Flash TTS and Flash-Lite TTS](https://blog.google/innovation-and-ai/models-and-research/gemini-models/gemini-3-8-text-to-speech/) are now available, in the Gemini API and [AI Studio](https://aistudio.google.com/generate-speech). Ranking #1 on Hume's Voice Design Benchmark, and on top of [Voice Arena](https://voicearena.com/tts-leaderboard/us-english) in 6 languages.

Biggest new features is that you can now replicate your own voice or create a new one from a sentence. The guide below shows how to do both.

### 1\. Record 2 clips

Same mic, same room, 24kHz mono. The API compares the two recordings, so don't switch from a headset to the laptop mic between them.

Bash

```bash
# macOS. ":0" is audio device 0. To find your mic:
# ffmpeg -f avfoundation -list_devices true -i ""
 
# me.wav: 15-20s of you talking like you normally do. Explain what
# you're building this week. Don't read, just talk.
ffmpeg -f avfoundation -i ":0" -ac 1 -ar 24000 -t 20 me.wav
 
# consent.wav: read this word for word:
# "I am the owner of this voice and I consent to Google using this voice to create a synthetic voice model."
ffmpeg -f avfoundation -i ":0" -ac 1 -ar 24000 -t 8 consent.wav
```

Linux: `-f alsa -i default`. On macOS, the first run may only open the microphone permission dialog. Allow it, then run the command again.

The consent sentence must be one of the [25 supported versions](https://ai.google.dev/gemini-api/docs/voice-replication#consent-phrases-by-language), read exactly. German, for example: *"Ich bin der Eigentümer dieser Stimme und bin damit einverstanden, dass Google diese Stimme zur Erstellung eines synthetischen Stimmmodells verwendet."* The reference clip can be in any language. Use the language you want the voice to speak later.

### 2\. Create the voice, then speak

Python

```python
import base64
from google import genai
 
client = genai.Client()
 
def b64(path):
    return base64.b64encode(open(path, "rb").read()).decode()
 
voice = client.voices.create(
    store=True,  # kept in your project for 1 year, returns voice_...
    voice={
        "model": "gemini-3.8-flash-tts",
        "type": "replicated",
        "display_name": "Me",
        "replicated": {
            "source_audio": {"mime_type": "audio/wav", "data": b64("me.wav")},
            "consent_audio": {"mime_type": "audio/wav", "data": b64("consent.wav")},
        },
    },
)
print(voice.id)
 
interaction = client.interactions.create(
    model="gemini-3.8-flash-tts",
    input=[{
        "type": "user_input",
        "content": [{
            "type": "text",
            "text": "Okay so... <short pause> I did not record this. <laugh> "
                    "Twenty seconds of audio and one consent sentence. That's it.",
            "annotations": [{"type": "speech_metadata", "style": "casual, a bit amused"}],
        }],
    }],
    response_format={"type": "audio"},
    generation_config={"speech_config": [{"voice": voice.id}]},
)
 
# 3.8 returns a real WAV with a RIFF header. No wave-module wrapping.
open("me_synth.wav", "wb").write(base64.b64decode(interaction.output_audio.data))
```

Two things to notice. The text is spoken word for word. The delivery ("casual, a bit amused") goes in `speech_metadata.style`, and the short sounds go inline as `<short pause>` and `<laugh>`. The voice ID is reusable: pass it in any later request, or find it again with `client.voices.list(type_=["replicated"])`.

If you don't want anything stored server-side, `store=False` returns an encrypted `voicekey_...` that you keep yourself. It works in the same `speech_config` field and expires after 7 days.

## Or design one from a sentence

No recordings needed. Same call, different `voice` dict. You also get a `sample_audio` preview, so you can listen to the voice before you synthesize anything:

Python

```python
voice = client.voices.create(
    store=True,
    voice={
        "model": "gemini-3.8-flash-tts",
        "type": "prompted",
        "display_name": "Deadpan host",
        "gender": "male",
        "language_code": "en-US",
        "prompted": {"input": "A dry, deadpan podcast host in his 30s, low pitch, slight German accent."},
    },
)
open("preview.wav", "wb").write(base64.b64decode(voice.sample_audio.data))
```

Then use `voice.id` exactly as above.

## What changed in prompting

If you're coming from `gemini-3.1-flash-tts-preview`, this will break your prompts, so read the [prompting guide](https://ai.google.dev/gemini-api/docs/speech-generation#prompting-guide) and the [migration notes](https://ai.google.dev/gemini-api/docs/speech-generation#migration). The short version:

- Input text is spoken word for word. Instructions written inside the text get spoken out loud too.
- Delivery that lasts the whole line ("whispering", "out of breath") goes in `speech_metadata.style`. Short sounds go inline in angle brackets.
- Multi-speaker turns need an explicit `speaker` on every turn.
- Long "Audio Profile" prompts now cause voice drift. Design the persona once with the Voices API, then send short or empty `style` strings.
- Non-streaming (unary) responses are real WAV (`audio/wav`), so remove any code that adds a WAV header. Set `response_format` to `audio/l16` if you still want raw PCM.