> ## Documentation Index
> Fetch the complete documentation index at: https://docs.coval.ai/llms.txt
> Use this file to discover all available pages before exploring further.
# Personas
> Define who the simulated user is and how they sound.
A **persona** defines who the simulated user is and how they sound — their voice, accent, personality, and speaking style. A persona pairs with a [test case](/concepts/test-sets/overview), which defines *what* the user is trying to do. Keep behavioral traits in the persona and task instructions in the test case — don't mix the two.
A persona has two parts:
* **Who they are** — the personality, goals, speaking style, and behavior, set through the [persona prompt and behavioral settings](#who-they-are).
* **How they sound** — the [voice, accent, and background noise](#how-they-sound) you configure.
A few additional [technical settings](#advanced) cover multilingual recognition, hold-music disconnects, and phone-number routing.
## Creating a persona
1. Navigate to the **Personas** section.
2. Click **Create New Persona**.
3. Give the persona a **Label** (its display name) and, optionally, customize the **Avatar** — select hair, eye, and lip styles, or regenerate the seed for a new base face.
4. Configure the settings below and save.
## Who they are
A persona's personality and behavior come from two places: the **Persona Characteristics** prompt and a few behavioral settings.
The **Persona Characteristics** prompt (required) describes the persona's demographics, personality, and communication style. The language model generates the persona's dialogue from this prompt, and the text-to-speech engine speaks that text — so emotion, hesitation, and pacing all come from *the words you tell the persona to use*, not from vocal controls. Use the expand button (Shift+E) for a full-screen editor.
### Emotional tone
Describe emotional behavior in terms of word choice and conversational patterns, not generic labels:
```
// Less effective
You are an angry customer.
// More effective
You are extremely frustrated and losing patience. You use short, clipped
sentences. When you have to repeat information you've already provided,
you use phrases like "I already told you this" and "This is unacceptable."
Your language becomes sharper and more aggressive as the conversation goes
on if the agent cannot resolve your issue quickly.
```
Punctuation acts as a speech cue for the TTS engine:
| Cue | Effect |
| --------------- | ------------------------------------------------------------------------ |
| `!` | Urgency or emphasis |
| `,` | Natural pause or hesitation |
| `-` | Brief break |
| Short sentences | Impatience or stress |
| `?!` | Disbelief |
| `...` (avoid) | Some TTS engines read it as "dot dot dot" — use commas or dashes instead |
Real callers escalate or de-escalate, so include emotional progression:
```
You start the call calmly but become increasingly frustrated if the agent
asks you to repeat information or puts you on hold. If the agent resolves
your issue, your tone should soften. If the agent is dismissive, you
become more insistent and demand to speak to a supervisor.
```
Higher-realism voices generally produce better emotional expressiveness — but they have a \~12 connection concurrency limit, so use higher-concurrency voices for high-volume runs where expressiveness matters less.
```
You are a customer under significant time pressure. You are calling during
your lunch break and need this resolved quickly. Keep your responses very
short and direct. You mention the time frequently and say things like
"Can we speed this up?" and "I really don't have much time." If the agent
asks unnecessary questions, respond with impatience: "Is that really
necessary right now?"
```
```
You are an older adult who is not comfortable with technology. You are
calling because you cannot figure out the website. You are somewhat
impatient and repeat yourself when you feel you're not being understood.
You become flustered when given too many steps at once and say things
like "That's too many things at once" or "Can you just do it for me?"
You occasionally go on brief tangents about how things used to be simpler.
```
```
You are disappointed with the service you received but remain polite
throughout the call. You express frustration through pointed questions
rather than harsh language. Use phrases like "I'm quite disappointed"
and "I was really expecting better." You give the agent a fair chance to
resolve the issue but make it clear that your patience has limits.
```
### Filler words
TTS engines process text literally — unusual spellings or repeated letters can cause them to spell out letters or mispronounce sequences. Use standard spellings:
| Use This | Avoid This | Why |
| ----------- | ------------------- | ------------------------------------- |
| `um` | `ummm`, `ummmm` | Extra letters may be spelled out |
| `uh` | `uhhh`, `uhhhhh` | Extra letters may be spelled out |
| `hmm` | `hmmmmm`, `hmmmmmm` | Extra letters may be spelled out |
| `oh` | `ohhh`, `ohhhh` | Extra letters may be spelled out |
| `ah` | `ahhh`, `ahhhh` | Extra letters may be spelled out |
| `well,` | `well...` | Ellipses may be read as "dot dot dot" |
| `so,` | `so...` | Ellipses may be read as "dot dot dot" |
| `you know,` | `you know...` | Ellipses may be read as "dot dot dot" |
Include explicit TTS-friendly instructions in the prompt:
```
You use natural filler words in conversation. When hesitating, use only
these words: "um", "uh", "hmm", "oh", "well". Write them as single short
words. Use commas for pauses instead of ellipses or repeated letters.
Example: "Um, I think the order number is, uh, let me check, it's 12345."
```
### Conversation triggers
To make the persona stay silent until the agent says a specific phrase (e.g. waiting for a greeting):
1. **Set the Conversation Initiator** to "Persona waits to speak" so the agent always speaks first.
2. **Use strong, repeated language** in the prompt:
```
CRITICAL INSTRUCTION: You MUST remain completely silent until the agent
says "How can I help you today?" Do not speak. Do not respond to any
other greeting or introduction. Wait specifically for the phrase
"How can I help you today?" before saying anything. Any other phrase
like "How may I assist you?" or "What can I do for you?" should NOT
trigger your response. Continue waiting silently.
```
3. **Keep the trigger phrase simple and distinctive** — shorter, common phrases are easier to detect reliably.
4. **Include fallback behavior** so the conversation doesn't stall:
```
If the agent does not say "How can I help you today?" within the first
30 seconds, you may begin speaking with your objective. This prevents the
conversation from stalling entirely.
```
Because the underlying model is probabilistic, trigger adherence is high but not perfectly deterministic. For mission-critical trigger behavior, run multiple simulations to account for natural variation.
### DTMF/IVR and call endings
In a voice persona prompt you can also specify navigation and call-control behavior — DTMF/IVR menu handling, speech style, when to provide or withhold information, and when to hang up.
```
You are a customer calling support.
- WAIT for all options before proceeding
- Use dtmf tool to select menu options
- Remain silent during IVR navigation
- Natural responses with occasional pauses
- Only respond when directly asked
Hang up if transferred to a human agent.
```
```
- Wait for the automated greeting before typing
- Respond naturally to prompts
- Natural chat language with occasional typos
- Concise responses unless asked for details
```
### Behavioral settings
Alongside the prompt, a few structured settings shape how the persona paces and times its speech during voice simulations.
| Setting | Options | Behavior |
| -------------------------- | --------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Conversation Initiator** | Persona waits to speak / Persona speaks first | Whether the persona waits for the agent to speak first or initiates the conversation. |
| **Interruption Rate** | None (default) / Low / Medium / High | How often the persona proactively interrupts the agent on a timer: never / \~90s / \~45s / \~30s. Simulates impatient or talkative callers. |
| **Silent Mode** | Off (default) / On | The persona stays completely silent and never responds — tests how the agent handles unresponsive callers or dead air. Enabling it automatically disables background sound, interruption rate, and conversation initiator. |
### Interruption and turn-taking
Voice simulations involve two distinct types of overlap:
* **Proactive interruptions** — controlled by the [Interruption Rate](#behavioral-settings) setting (None / Low / Medium / High). When set to None, the persona never deliberately talks over the agent.
* **Natural turn-taking overlap** — even at None, the persona may start speaking while the agent is still talking, because the speech-to-text engine interprets a brief pause as end-of-turn. This mirrors how real callers sometimes talk over agents.
To make the persona more patient and reduce overlap, add explicit waiting instructions and slower speech patterns to the prompt:
```
Always wait for the agent to completely finish their thought before
responding. Take a brief pause after the agent stops speaking before
you begin your response. If you hear the agent start speaking again,
stop immediately and let them finish.
```
```
You are a thoughtful, patient caller who considers the agent's words
carefully before responding. You take a moment to think before speaking.
```
## How they sound
Configure the persona's voice and audio environment.
| Setting | Description |
| --------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Voice** | Select from the voice catalog. Each voice carries vocal-presentation and accent metadata and has a preview. |
| **Voice Pitch** | Filter voices by a low, medium, or high curated pitch profile. This narrows the catalog to a different underlying voice — it is **not** a pitch-shifting effect applied after synthesis. |
| **Language & Accent** | Choose language and regional accent. Supported languages vary by voice: English, Spanish, French, French (Canada), German, Hindi, Korean, Arabic, Hebrew, Bulgarian, Danish, Lithuanian, and Polish. Arabic and Hebrew transcripts render in their native script with right-to-left alignment. |
| **Background Noise** | Add ambient noise to simulate real-world call conditions. Choose from the built-in library or [upload your own](#custom-background-sounds). Volume is adjustable with a slider. |
Voices fall into two categories based on realism and concurrency. Higher-realism voices sound more natural and expressive but support only \~12 simultaneous connections — for high-volume runs, use higher-concurrency voices to avoid bottlenecks.
**Higher Concurrency (34 voices)**
| Voice | Accent / Language | Presentation |
| -------- | ----------------- | ------------ |
| Aria | Multiple | Feminine |
| Ashwin | Multiple | Masculine |
| Autumn | Multiple | Feminine |
| Brynn | Multiple | Feminine |
| Callum | Multiple | Masculine |
| Caspian | Multiple | Masculine |
| Corwin | Multiple | Masculine |
| Darrow | Multiple | Masculine |
| Delphine | Multiple | Feminine |
| Dorian | Multiple | Masculine |
| Elara | Multiple | Feminine |
| Kieran | Multiple | Masculine |
| Lysander | Multiple | Masculine |
| Marina | Multiple | Feminine |
| Naveen | Multiple | Masculine |
| Orion | Multiple | Masculine |
| Rowan | Multiple | Masculine |
| Emma | American | Feminine |
| Kent | American | Masculine |
| Sydney | American | Feminine |
| John | American | Masculine |
| Eva | British | Feminine |
| Jack | British | Masculine |
| Zoey | American | Feminine |
| Harper | American | Feminine |
| Riley | American | Feminine |
| Skyler | American | Feminine |
| Quinn | American | Feminine |
| Lukas | Eastern European | Masculine |
| Soren | Multiple | Masculine |
| Skye | Multiple | Feminine |
| Vera | Multiple | Feminine |
| Isabella | Latin America | Feminine |
| Alexei | Eastern European | Masculine |
**Higher Realism (37 voices) — Limited Concurrency**
| Voice | Accent / Language | Presentation |
| -------------- | ----------------- | ------------ |
| Alejandro | Latin America | Masculine |
| Angela | American | Feminine |
| Erika | Latin America | Feminine |
| Harry | Multilingual | Masculine |
| Amir | Arabic | Masculine |
| Layla | Arabic | Feminine |
| Noa | Hebrew | Feminine |
| Yossi | Hebrew | Masculine |
| Mark | American | Masculine |
| Monika | Indian | Feminine |
| Raju | Indian | Masculine |
| Kehinde | Nigerian | Feminine |
| Victor | Nigerian | Masculine |
| Luis | Spanish-Accented | Masculine |
| Lisa | Spanish-Accented | Feminine |
| Leo | Spanish-Accented | Masculine |
| Martin | Spanish-Accented | Masculine |
| Marshal | German-Accented | Masculine |
| Raven | German-Accented | Feminine |
| Puthina | Malay | Feminine |
| Darryl | Malay | Masculine |
| Juvy | Filipino | Feminine |
| Pedro | Filipino | Masculine |
| Rachel | Filipino | Feminine |
| Burak | Turkish-Accented | Masculine |
| Walker | US Southern | Feminine |
| Cletus | US Southern | Masculine |
| Bubba | US Southern | Masculine |
| Cowboy Chris | US Southern | Masculine |
| Miss Sally May | US Southern | Feminine |
| Jay | Chinese-Accented | Masculine |
| Ziyu | Chinese-Accented | Feminine |
| Isla | Scottish | Feminine |
| Chris | Scottish | Masculine |
| Alok | Indian | Masculine |
| Mani | Indian | Masculine |
| Vidya | Indian | Feminine |
**Concurrency limit:** Higher-realism voices support a maximum of \~12 simultaneous connections. For high-volume runs, use higher-concurrency voices to avoid bottlenecks.
| Sound | Description |
| ----------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| **Off** | No background noise (default) |
| **Office** | Office ambience |
| **Lounge** | People in a lounge |
| **Crowd Talking** | Crowd conversation noise |
| **Airport Boarding** | Airport boarding announcements |
| **Bus Interior** | Inside a bus |
| **Kids Playing** | Playground sounds |
| **Doorbell** | Doorbell ringing |
| **Train Arrival** | Train station arrival sounds |
| **Portable AC** | Air conditioner hum |
| **Skatepark** | Skatepark ambience |
| **Small Dog Bark** | Small dog barking |
| **Cafe** | Cafe ambience |
| **Ferry Announcement** | Ferry and PA announcements |
| **Heavy Rain** | Heavy rainfall |
| **Moderate Wind** | Wind sounds |
| **Newborn Baby Crying** | Baby crying |
| **Office with Alarm** | Office with alarm going off |
| **Street with Sirens** | Street traffic with sirens |
| **Construction Work** | Construction site noise |
| **Backchanneling** | Short listener cues like "mm-hmm" and "yeah" that simulate an engaged caller. Use this to test whether your agent responds naturally to an attentive, responsive caller. |
### Custom background sounds
Beyond the built-in library, you can upload your own background sound — for example, a recording of your own call center floor, your hold music, or a specific noise profile you want to test against. Uploaded sounds are private to your organization and appear in the same picker alongside the built-in options.
In the persona's background-sound picker, choose to upload a file. Give it a name and select a `.wav` or `.mp3` file.
Once the upload completes, the sound appears in the picker. Select it like any built-in sound and set the volume with the slider.
During voice simulations, the sound is mixed into the persona's side of the conversation and loops for the duration of the call.
| Detail | Value |
| --------------------- | ------------------------------------------------------------------------------------------------- |
| **Supported formats** | WAV (`.wav`) and MP3 (`.mp3`) |
| **Maximum file size** | 50 MB |
| **Volume** | Adjustable with the slider (0–100%). Each sound has a default level you can override per persona. |
| **Availability** | Private to your organization; appears alongside the built-in sounds. |
Pick a sound that loops cleanly if you expect long calls — the file repeats for the length of the conversation, so an abrupt cut or trailing silence will be noticeable.
## Advanced
The persona configuration modal's **Advanced** panel covers multilingual recognition, hold-music disconnects, custom text configuration, and agent-voice routing.
### Multi-Language STT
Found under **Advanced** in the persona configuration modal. Enables multilingual speech recognition so the persona can accurately hear and respond to agents that speak multiple languages in the same conversation (e.g. "For English press one, Para español presione dos").
| Setting | Description |
| ----------------- | ------------------------------------------------------------------------------------------------------------------------------------------- |
| **Off** (default) | Speech recognition is locked to the persona's configured language for best single-language accuracy. |
| **On** | Accepts all supported languages simultaneously: English, Spanish, French, German, Hindi, Russian, Portuguese, Japanese, Italian, and Dutch. |
To test the same agent with and without multilingual recognition, clone a persona and toggle this on the copy.
### Hold Music Timeout
Found under **Advanced** in the persona configuration modal. Disconnects the persona after a period of silence or hold music, instead of waiting for the default timeout.
| Setting | Description |
| ----------------- | ---------------------------------------------------------------------------------- |
| **Off** (default) | Standard timeout behavior. |
| **On** | Disconnects after the specified number of seconds (5–300) with no speech activity. |
Useful for testing live-agent transfer flows — set it to 10–15 seconds to confirm the transfer happened without sitting through extended hold music.
## Version history
Every config-changing save of a persona — its prompt, voice, language, or behavioral settings — is recorded in its version history, so you can see how the persona changed over time and tell which version a run used. See [Versioning](/concepts/versioning/overview) for how copy-on-save works and how to pull the history through the [v1 API](/api-reference/v1/personas/personas/list-persona-versions).
### Caller phone number
Coval uses different phone numbers depending on the simulation type. Assign a specific phone number index to a persona if your workflow depends on phone-number routing.
| Index | Phone Number |
| ----- | ------------ |
| 1 | +16504471573 |
| 2 | +16506400392 |
| 3 | +16506329775 |
| 4 | +16505360811 |
| 5 | +16505360576 |
| 6 | +15418450089 |
| 7 | +15412194880 |
| 8 | +14157181081 |
| 9 | +14157180538 |
| 10 | +14157180269 |
| 11 | +14153765034 |
| 12 | +14069058267 |
| 13 | +14066920094 |
| 14 | +14064159042 |
| 15 | +14063022479 |
| 16 | +14063022353 |
| 17 | +17182801764 |
| 18 | +17182858503 |
| 19 | +17182859858 |
| 20 | +17183051836 |
| 21 | +17187195385 |
| 22 | +17187195407 |
| 23 | +15342172296 |
| 24 | +15342172366 |
| 25 | +15342172371 |
| 26 | +15342172387 |
| 27 | +19855295712 |
| 28 | +19858539008 |
| 29 | +19858539188 |
| Index | Phone Number |
| ----- | ------------ |
| 1 | +14158734019 |
| 2 | +17199853850 |
| 3 | +17199853656 |
| 4 | +17196219208 |
| 5 | +17194630332 |
| 6 | +17194630202 |
| 7 | +17194630116 |
| 8 | +17194510465 |
| 9 | +16309315617 |
| 10 | +16309190593 |
| 11 | +16306014871 |
| 12 | +16305857118 |
| 13 | +16305526080 |
| 14 | +16305222063 |
| 15 | +16304468895 |
| 16 | +12624037199 |
| 17 | +12623988133 |
| 18 | +12622149045 |