Voice Lab

Voice Lab lets you create custom hybrid voices by blending 2-4 existing Aero TTS voices together. Adjust the weight of each voice to craft a unique sound that matches your brand.

How Voice Mixing Works

When you create a voice mix, Aero TTS blends the acoustic characteristics of multiple voices based on the weights you assign. Higher weight means more influence from that voice.

Voice Mix = Voice A (weight 1.5) + Voice B (weight 0.8)

The result is a new voice that combines qualities from both — for example, the warmth of one voice with the clarity of another.

Creating a Voice Mix

In the Dashboard

1. Go to Aero TTS > Voice Lab.
2. Click Create Mix.
3. Select 2-4 base voices.
4. Adjust the weight slider for each voice (0.1 to 10.0).
5. Enter a name and optional description.
6. Click Preview to hear the result.
7. Click Save to create the mix.

Your mix appears as a custom voice in the playground and API.

Via API

curl -X POST https://api.thinnest.ai/api/tts/voice-mixes \
  -H "Authorization: Bearer thns_sk_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Warm Professional",
    "voices": [
      { "voice": "aero-vayu", "weight": 1.5 },
      { "voice": "aero-aria", "weight": 0.8 }
    ],
    "description": "Blend of Vayu warmth with Aria friendliness"
  }'

Response:

{
  "voice_id": "mix_abc123",
  "name": "Warm Professional",
  "mix_config": [
    { "voice": "aero-vayu", "weight": 1.5 },
    { "voice": "aero-aria", "weight": 0.8 }
  ]
}

Using a Voice Mix

Once created, use the mix voice_id in any synthesis request:

curl -X POST https://api.thinnest.ai/api/tts/synthesize \
  -H "Authorization: Bearer thns_sk_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "text": "This is my custom blended voice.",
    "voice": "mix_abc123",
    "model": "aero",
    "format": "mp3"
  }' \
  --output custom-voice.mp3

You can also pass voice_mix inline without saving a mix:

curl -X POST https://api.thinnest.ai/api/tts/synthesize \
  -H "Authorization: Bearer thns_sk_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "text": "Inline voice mixing without saving.",
    "voice": "aero-vayu",
    "model": "aero",
    "voice_mix": [
      { "voice": "aero-vayu", "weight": 1.5 },
      { "voice": "aero-kian", "weight": 0.5 }
    ],
    "format": "mp3"
  }' \
  --output inline-mix.mp3

Mix Parameters

Weight Guidelines

Tips for Great Mixes

• Start with 2 voices — More voices make results less predictable.
• Use similar languages — Mixing en-us and en-gb voices works well. Cross-language mixing may produce unexpected results.
• Balance weights — A 1.5:0.8 ratio sounds natural. Extreme ratios (10:0.1) essentially use one voice.
• Test with varied text — A mix that sounds good for short phrases may behave differently with long paragraphs.
• Name descriptively — "Warm Professional" is more useful than "Mix 1".

Managing Mixes

List Your Mixes

curl https://api.thinnest.ai/api/tts/voice-mixes \
  -H "Authorization: Bearer thns_sk_YOUR_KEY"

Delete a Mix

curl -X DELETE https://api.thinnest.ai/api/tts/voice-mixes/mix_abc123 \
  -H "Authorization: Bearer thns_sk_YOUR_KEY"

Deleting a mix does not affect past audio generated with it. Future synthesis requests using the deleted mix ID will fail.

Limits

• Maximum 4 voices per mix
• Minimum 2 voices per mix
• Mix name must be 1-100 characters
• Mixes are per-user — not shared across team members