Sent by the server when in server_vad mode to indicate that speech has been detected in the audio buffer. This can happen any time audio is added to the buffer (unless speech is already detected). The client may want to use this event to interrupt audio playback or provide visual feedback to the user.

The client should expect to receive a input_audio_buffer.speech_stopped event when speech stops. The item_id property is the ID of the user message item that will be created when speech stops and will also be included in the input_audio_buffer.speech_stopped event (unless the client manually commits the audio buffer during VAD activation).

interface InputAudioBufferSpeechStartedEvent {
    audio_start_ms: number;
    event_id: string;
    item_id: string;
    type: "input_audio_buffer.speech_started";
}

Properties

audio_start_ms: number

Milliseconds from the start of all audio written to the buffer during the session when speech was first detected. This will correspond to the beginning of audio sent to the model, and thus includes the prefix_padding_ms configured in the Session.

event_id: string

The unique ID of the server event.

item_id: string

The ID of the user message item that will be created when speech stops.

type: "input_audio_buffer.speech_started"

The event type, must be input_audio_buffer.speech_started.