how to use google speech API to convert audio files to string?

I am trying to use Google Speech API to convert audio files to strings but I can’t make it work when I try to transcribe an audio file that is uploaded by my form element.

<Form onSubmit={handleSubmit}>
        <input type="file" ref={audioFileRef} />
        <Button>Import</Button>
</Form>

This is my fetch:

fetch(path, {
      method: "POST",
      headers: {
        "Content-Type": "audio/wave",
      },
      body: formData,
    })

This is the server:

async function main(content) {
  const client = new speech.SpeechClient();

  const config = {
    encoding: "LINEAR16",
    sampleRateHertz: 16000,
    languageCode: "en-US",
  };

  const audio = {
    uri: content,
  };

  const request = {
    audio: audio,
    config: config,
  };

  const [response] = await client.recognize(request);

  return await response.results
    .map((result) => result.alternatives[0].transcript)
    .join("n");
}

app.post("/import-audio", async (req, res) => {
  const transcription = main(req.body);
  transcription.then(console.log).catch(console.error);
});

I am trying to transcribe the audio file from the form element