Voice Personalities

Overview

A personality is an optional free-form description attached to a voice profile — who this voice is, how they speak, what they care about. Set one and two new controls appear next to the generate button, both powered by a bundled Qwen3 LLM running entirely locally:

• Compose — drop a fresh in-character line into the textarea. Click again for a different take.
• Speak in character — a toggle that rewrites your input text in the character's voice before TTS, preserving every idea.

The LLM produces the text. The voice profile speaks it. No cloud round-trip, no external API — the whole loop runs on your hardware.

Setting a personality

Open a voice profile's edit view. The Personality field is free-form text up to 2,000 characters. Describe the voice however helps you — past lines they'd say, speech patterns, tone, boundaries.

Good descriptions tend to include:

• A one-line identity (who they are)
• Speech patterns (rhythm, vocabulary, what they avoid)
• Representative phrases — example lines show the LLM the target tone better than adjectives
• What the character wouldn't do (they don't explain, they don't apologize, they refuse to break character, etc.)

You can set a personality on any voice profile type — cloned or preset. The three modes work identically regardless of engine.

The two actions

Each action is tuned for a specific job and the LLM temperature is adjusted to match.

Compose

Generate a fresh utterance in the character's voice, with no seed text. Click the shuffle button to drop a line straight into the generate textarea; click again for a different take.

• When to use: prototyping, sampling a character's voice, brainstorming a line without typing one first
• Temperature: hot — variety is the point
• Typical output: a short, punchy line that fits the character's register

Speak in character (rewrite)

Flip the persona toggle and whatever you type (or dictate) gets rewritten in the character's voice before TTS — every idea preserved, only the phrasing changes. High-fidelity mode: the content doesn't change, only the voice does.

• When to use: turning a dictated memo into in-character speech; lifting a plain-English script into a specific voice without editing by hand
• Temperature: cold — faithfulness wins
• Typical output: same ideas, same order, different phrasing and cadence

Speech-only framing

Both modes enforce speech-only output. The LLM is prompted to produce things a person would actually say out loud — no narration, no action tags (*sighs*, [laughs]), no meta-commentary, no markdown formatting, no stage directions.

This is deliberate: the output is going straight into TTS, and anything that isn't speakable ends up either ignored or read literally. The speech-only framing also makes the output land cleanly inside dialogue, so you can drop a Respond result straight into a Story.

The local LLM

The bundled LLM is Qwen3, available in three sizes:

The model runs through the same backend split Sonna already uses for TTS — MLX (4-bit community quants) on Apple Silicon, PyTorch (transformers AutoModelForCausalLM) everywhere else. Downloads go through the same cache and model-management UI as TTS models.

Pick a size in Settings → Captures → Refinement → Refinement model — the personality modes reuse it. If you switch models, both refinement and personality output pick up the change on the next call.

Using the controls

Both controls appear on the floating generate box when the selected profile has a personality set.

Compose always gives you something different on re-click. The persona toggle, on the other hand, is a mode — it applies to every generate call until you flip it back off.

Use cases

• Agents that speak in a voice you own. Combine the persona toggle with the built-in MCP Server so Claude Code, Cursor, Cline, or any MCP-aware agent can talk back through a profile with a personality. The agent calls sonna.speak({ text, profile, personality: true }) and Sonna rewrites the text in character before speaking.
• Interactive characters. Games, narrative tools, accessibility experiences. A character with a personality description plus a cloned voice becomes a reusable prop.
• Accessibility. People who can't speak in their original voice can keep a personality description of how they used to sound and use the rewrite toggle to turn typed input into in-character speech.
• Creative drafting. Write a plain outline, flip the persona toggle, generate line-by-line into the character's voice, drop the audio into a Story.

API surface

Personalities are accessible via REST:

POST /generate with personality: true is the same primitive MCP's sonna.speak tool uses when you pass personality: true. Scripts and agents can use it directly.

Limits and gotchas

• The personality is a prompt, not a fine-tune. The LLM will sometimes drift out of character, especially on Compose at high temperature. Click again for another take.
• Long personalities are not always better. 2,000 chars is a ceiling, not a goal. A sharp 300-char description with two example lines typically outperforms a long one.
• Speech-only framing is enforced, but not bulletproof. Very large prompts or unusual inputs can sneak an action tag through. If you see [laughs] in TTS output, it's usually a personality-field hint the model anchored onto — remove it from the description.
• Rewrite is stricter than Respond. If the output is changing your meaning, you probably want Respond (or a wholesale Compose with context in the input), not Rewrite.

Next steps