sending audio file to open ai whisper model

I am converting my recorded audio file to a blob object and then reading it with file reader to make a post request to open ai whisper modelIt expects a audio file and model name i.e whisper-1

The error i am getting is

1 validation error for Request\nbody -> file\n field required (type=value_error.missing)

my code is below

  const handleUpload = () => {    const audioBlob = new Blob(audioChunks, { type: "audio/webm" });    const reader = new FileReader();    reader.readAsDataURL(audioBlob);    reader.onload = async () => {      const audioBase64 = await reader.result.split(",")[1];      const payload = {        audio: audioBase64,        model: "whisper-1",      };      const payloadString =  JSON.stringify(payload);      fetch("https://api.openai.com/v1/audio/transcriptions", {        method: "POST",        headers: {"Content-Type": "application/json",          Authorization: `Bearer ${key}`,        },        body: payloadString,      })        .then((response) => response.json())        .then((data) => console.log(data))        .catch((error) => console.error(error));    };  };