var params = {
  text: "Hello",
  voice: "en-US_MichaelVoice",
  access_token: "<ACCESS_TOKEN>"
};

stream = WatsonSpeech.TextToSpeech.synthesize(params);

https://stream.watsonplatform.net/text-to-speech/api/v1/synthesize?voice=en-US_MichaelVoice&text=Hello&watson-token=**undefined**

module.exports = function synthesize(options) {
  if (!options || (!options.token && !options.access_token)) {
    throw new Error('Watson TextToSpeech: missing required parameter: options.token (CF) or options.access_token (RC)');
  }
  options['watson-token'] = options.token;
  delete options.token;
  var audio = options.element || new Audio();