ElevenLabsMediumUltra

ElevenLabs Eleven v4

ElevenLabs Eleven v4 text-to-speech via Fal.AI. Expressive speech with inline audio tags ([whispering], [excited]), IPA pronunciation, stability/similarity controls, up to 5,000 characters per request and optional character-level timestamps.

186 credits

per 1000 characters (0.186 credits/char, billed per character)

Expressive delivery steered by inline audio tags like [whispering] and [excited]

IPA pronunciation control enclosed in forward slashes

Stability and similarity controls to shape delivery

Up to 5,000 characters per request with optional character-level timestamps

Run it right now

Test this model instantly in the Console Playground — no code required

Use with AI Assistant

Copy usage instructions for Claude, ChatGPT, or other AI

llms.txtllms.txt ↗

Quick Start

curl -X POST "https://api.core.today/v1/predictions" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: cdt_your_api_key" \
  -d '{
  "model": "elevenlabs/tts/eleven-v4",
  "input": {
    "text": "[excited] Hello! Welcome to Eleven v4.",
    "voice": "Aria"
  }
}'

Parameters

Parameter	Type	Required	Default	Description
`text`	string	Yes	-	The text to convert to speech (max 5,000 characters, billed per character). Supports audio tags such as [whispering] or [excited] and IPA pronunciation enclosed in forward slashes.
`voice`	string	No	Rachel	The voice to use — an ElevenLabs premade voice name (e.g. Rachel, Aria, Roger, Sarah, George) or a voice ID.
`stability`	number	No	0.5	Voice stability (0-1). Lower values allow more expressive delivery; higher values make delivery more consistent.
`similarity_boost`	number	No	0.75	How closely the output follows the reference voice (0-1). Higher values increase similarity but may reduce naturalness.
`language_code`	string	No	-	Language code (ISO 639-1, e.g. en, ko, ja) for speech generation and text normalization. Auto-detected when omitted.
`apply_text_normalization`	string	No	auto	Whether to normalize text such as numbers and dates before generation. autoonoff
`output_format`	string	No	mp3_44100_128	Output audio format, formatted as codec_sample_rate_bitrate (MP3 variants). mp3_22050_32mp3_44100_32mp3_44100_64mp3_44100_96mp3_44100_128mp3_44100_192
`timestamps`	boolean	No	false	Whether to return character-level timing information with the generated audio.
`seed`	integer	No	-	Seed for best-effort reproducibility. Identical output is not guaranteed.

Common Parameters

Common parameters used when calling POST /v1/predictions.

Parameter	Type	Required	Default	Description
`model`	string	Yes	-	Model identifier
`input`	object	Yes	-	Object containing the model-specific parameters from the table above
`output_folder`	string	No	-	Folder path for output files (max 256 chars, '..' not allowed)
`webhook_url`	string	No	-	Webhook URL to call on completion
`is_public`	boolean	No	false	If true, output files are also available via permanent public URLs

Examples

Excited greeting

A short line using an audio tag to set an excited delivery.

curl -X POST "https://api.core.today/v1/predictions" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: cdt_your_api_key" \
  -d '{
  "model": "elevenlabs/tts/eleven-v4",
  "input": {
    "text": "[excited] Hello! Welcome to Eleven v4.",
    "voice": "Aria"
  }
}'

Whispered Korean narration

Korean narration with a whispered delivery and an explicit language code.

curl -X POST "https://api.core.today/v1/predictions" \
  -H "Content-Type: application/json" \
  -H "X-API-Key: cdt_your_api_key" \
  -d '{
  "model": "elevenlabs/tts/eleven-v4",
  "input": {
    "text": "[whispering] 조용히 해 봐요. 숲이 잠들고 있어요.",
    "voice": "Rachel",
    "language_code": "ko",
    "stability": 0.4
  }
}'