Realtime Transcription Session Create Response

• RealtimeTranscriptionSessionCreateResponse object \{ id, object, type, 3 more \}

  A Realtime transcription session configuration object.

  • id: string

    Unique identifier for the session that looks like sess_1234567890abcdef.

  • object: string

    The object type. Always realtime.transcription_session.

  • type: "transcription"

    The type of session. Always transcription for transcription sessions.

    • "transcription"

  • audio: optional object \{ input \}

    Configuration for input audio for the session.

    • input: optional object \{ format, noise_reduction, transcription, turn_detection \}

      • format: optional RealtimeAudioFormats

        The PCM audio format. Only a 24kHz sample rate is supported.

        • PCMAudio object \{ rate, type \}

          The PCM audio format. Only a 24kHz sample rate is supported.

          • rate: optional 24000

            The sample rate of the audio. Always 24000.

            • 24000

          • type: optional "audio/pcm"

            The audio format. Always audio/pcm.

            • "audio/pcm"

        • PCMUAudio object \{ type \}

          The G.711 μ-law format.

          • type: optional "audio/pcmu"

            The audio format. Always audio/pcmu.

            • "audio/pcmu"

        • PCMAAudio object \{ type \}

          The G.711 A-law format.

          • type: optional "audio/pcma"

            The audio format. Always audio/pcma.

            • "audio/pcma"

      • noise_reduction: optional object \{ type \}

        Configuration for input audio noise reduction.

        • type: optional NoiseReductionType

          Type of noise reduction. near_field is for close-talking microphones such as headphones, far_field is for far-field microphones such as laptop or conference room microphones.

          • "near_field"

          • "far_field"

      • transcription: optional object \{ language, languages, model, prompt \}

        Configuration of the transcription model.

        • language: optional string

          The language of the input audio.

        • languages: optional array of string

          The possible input audio languages configured for transcription, in ISO-639-1 format.

        • model: optional string or "whisper-1" or "gpt-transcribe" or "gpt-live-transcribe" or 5 more

          The model used for transcription. Current options are whisper-1, gpt-transcribe, gpt-live-transcribe, gpt-4o-mini-transcribe, gpt-4o-mini-transcribe-2025-12-15, gpt-4o-transcribe, gpt-4o-transcribe-diarize, and gpt-realtime-whisper.

          • string

          • "whisper-1" or "gpt-transcribe" or "gpt-live-transcribe" or 5 more

            The model used for transcription. Current options are whisper-1, gpt-transcribe, gpt-live-transcribe, gpt-4o-mini-transcribe, gpt-4o-mini-transcribe-2025-12-15, gpt-4o-transcribe, gpt-4o-transcribe-diarize, and gpt-realtime-whisper.

            • "whisper-1"

            • "gpt-transcribe"

            • "gpt-live-transcribe"

            • "gpt-4o-mini-transcribe"

            • "gpt-4o-mini-transcribe-2025-12-15"

            • "gpt-4o-transcribe"

            • "gpt-4o-transcribe-diarize"

            • "gpt-realtime-whisper"

        • prompt: optional string

          The prompt configured for input audio transcription, when present.

      • turn_detection: optional RealtimeTranscriptionSessionTurnDetection or null

        Configuration for turn detection. Can be set to null to turn off. Server VAD means that the model will detect the start and end of speech based on audio volume and respond at the end of user speech. For gpt-realtime-whisper, this must be null; VAD is not supported.

        • prefix_padding_ms: optional number

          Amount of audio to include before the VAD detected speech (in milliseconds). Defaults to 300ms.

        • silence_duration_ms: optional number

          Duration of silence to detect speech stop (in milliseconds). Defaults to 500ms. With shorter values the model will respond more quickly, but may jump in on short pauses from the user.

        • threshold: optional number

          Activation threshold for VAD (0.0 to 1.0), this defaults to 0.5. A higher threshold will require louder audio to activate the model, and thus might perform better in noisy environments.

        • type: optional string

          Type of turn detection, only server_vad is currently supported.

  • expires_at: optional number

    Expiration timestamp for the session, in seconds since epoch.

  • include: optional array of "item.input_audio_transcription.logprobs"

    Additional fields to include in server outputs.

    • item.input_audio_transcription.logprobs: Include logprobs for input audio transcription.

    • "item.input_audio_transcription.logprobs"