Whisper-1 Model Transcribes English Audio Incorrectly

Brass Contributor

Jul 22, 2025

You can force Whisper-1 to lock onto English by explicitly passing a "language": "en" parameter in your transcription request.

Since the current Azure.AI.OpenAI SDK (v2.2.0-beta.4) doesn’t yet expose a Language property, you’ll need to call the REST endpoint directly.

POST https://{your-resource-name}.openai.azure.com/openai/deployments/whisper-1/audio/transcriptions?api-version=2024-02-15-preview
Content-Type: application/json
Authorization: Bearer {your-key}

{
  "file": "<base64-or-stream-of-your-audio>",
  "model": "whisper-1",
  "language": "en"
}

This tells Whisper to skip auto-detection and transcribe everything as English

But, If you’d rather stay in the SDK, keep an eye out for the next preview of Azure.AI.OpenAI (v2.3.0+), where ConversationInputTranscriptionOptions

InputTranscriptionOptions = new()
{
    Model    = "whisper-1",
    Language = "en"
};

Once that lands, you can set Language = "en" directly in your C# code

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Whisper-1 Model Transcribes English Audio Incorrectly

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