audioUploadStream.js

app.post('/audio-upload', (req, res) => {
  var form = new formidable.IncomingForm();
  form.uploadDir = './audio'; //set upload directory
  form.keepExtensions = true;
  form.type = true;
  form.parse(req, function(err, fields, files) {
    console.log(files);
  });
  form.on('file', function(field, file) {
    require('fs').rename(
      file.path,
      require('path').join(form.uploadDir, 'myAudio.ogg')
    );
  });
});