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PrathameshDeshmukh's avatar
PrathameshDeshmukh
Copper Contributor
Jun 24, 2025

Whisper-1 Model Transcribes English Audio Incorrectly

Hi everyone,

I'm currently working with the gpt-4o-realtime-preview model from Azure OpenAI and using the whisper-1 model for audio-to-text transcription. However, I'm encountering a recurring issue where the transcription frequently fails to detect the correct language.

Even though I provide clear English audio, the output is often transcribed in other languages such as Hindi, Urdu, or Chinese. This inconsistency is affecting the reliability of the transcription process.

Here’s a snippet of the code I’m using:

ConversationSessionOptions sessionOptions = new()

{

    Voice = ConversationVoice.Alloy,

    InputAudioFormat = ConversationAudioFormat.Pcm16,

    OutputAudioFormat = ConversationAudioFormat.Pcm16,

    Instructions = instructions,

    InputTranscriptionOptions = new()

    {

        Model = "whisper-1",

    },

};

Is there a way to explicitly specify or prompt the whisper-1 model to prioritize or lock in English as the transcription language? Any guidance on how to improve language detection accuracy would be greatly appreciated.

Thanks in advance!

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1 Reply

  • hazem's avatar
    hazem
    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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