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ElevenLabs Eleven v4 Turbo

ElevenLabs Eleven v4 Turbo text-to-speech via Fal.AI. The Turbo tier of Eleven v4 at half the rate, with the same audio tags, IPA pronunciation, voice controls and optional character-level timestamps.

93 credits
per 1000 characters (0.093 credits/char, billed per character)
Half the per-character rate of Eleven v4
Same audio tags ([whispering], [excited]) and IPA pronunciation support
Stability and similarity controls
Up to 5,000 characters per request with optional character-level timestamps

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Use with AI Assistant

Copy usage instructions for Claude, ChatGPT, or other AI

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-turbo",
  "input": {
    "text": "[excited] Hello! Welcome to Eleven v4.",
    "voice": "Aria"
  }
}'

Parameters

ParameterTypeRequiredDefaultDescription
textstringYes-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.
voicestringNoRachelThe voice to use โ€” an ElevenLabs premade voice name (e.g. Rachel, Aria, Roger, Sarah, George) or a voice ID.
stabilitynumberNo0.5Voice stability (0-1). Lower values allow more expressive delivery; higher values make delivery more consistent.
similarity_boostnumberNo0.75How closely the output follows the reference voice (0-1). Higher values increase similarity but may reduce naturalness.
language_codestringNo-Language code (ISO 639-1, e.g. en, ko, ja) for speech generation and text normalization. Auto-detected when omitted.
apply_text_normalizationstringNoautoWhether to normalize text such as numbers and dates before generation.
autoonoff
output_formatstringNomp3_44100_128Output audio format, formatted as codec_sample_rate_bitrate (MP3 variants).
mp3_22050_32mp3_44100_32mp3_44100_64mp3_44100_96mp3_44100_128mp3_44100_192
timestampsbooleanNofalseWhether to return character-level timing information with the generated audio.
seedintegerNo-Seed for best-effort reproducibility. Identical output is not guaranteed.

Common Parameters

Common parameters used when calling POST /v1/predictions.

ParameterTypeRequiredDefaultDescription
modelstringYes-Model identifier
inputobjectYes-Object containing the model-specific parameters from the table above
output_folderstringNo-Folder path for output files (max 256 chars, '..' not allowed)
webhook_urlstringNo-Webhook URL to call on completion
is_publicbooleanNofalseIf 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-turbo",
  "input": {
    "text": "[excited] Hello! Welcome to Eleven v4.",
    "voice": "Aria"
  }
}'

App notification

A concise, consistent notification line with higher stability.

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-turbo",
  "input": {
    "text": "Your order has shipped and will arrive tomorrow.",
    "voice": "Roger",
    "stability": 0.8
  }
}'

Tips & Best Practices

1Billing counts every character of text, including audio tags.
2Prototype scripts on Turbo, then switch to Eleven v4 if you need the flagship tier for the final take.
3Raise stability for short system prompts that must sound identical every time.
4Choose an MP3 bitrate that fits the channel โ€” 32-64 kbps is enough for telephony-style playback.

Use Cases

High-volume voiceover where cost per character matters
Product UI prompts, notifications and IVR messages
Drafting narration before a final Eleven v4 render
Localized voice content across many short scripts