Request allowlist access for Gemini 2.5 Flash TTS audio output on Vertex AI (Hindi educational app)

Gemini API
1

Hi Google AI team,

I’m building a backend API for an educational web application that generates Hindi audio from text using Gemini TTS (warm, welcoming tone; normal pace).

“Modified by moderator”
Location: us-central1
Model: gemini-2.5-flash-tts

Authentication is working, but calls to :generateContent with responseModalities: [‘AUDIO’] fail with:
{
“error”: {
“code”: 400,
“message”: “You are not allowlisted to request audio output.”,
“status”: “INVALID_ARGUMENT”
}
}

Please add my project to the allowlist for Gemini TTS audio output.

Thank you!