Save the speech from a text into a mp3 file locally

saveSpeechLocally.js

const saveSpeechLocally = text => getSpeech(text).then(saveSpeech)

const getSpeech = text => {
  const Text = cleanText(text)
  const OutputFormat = 'mp3'
  const VoiceId = 'Kimberly'
  const params = { Text, OutputFormat, VoiceId }
  return polly.synthesizeSpeechAsync(params)
}

const saveSpeech = ({ AudioStream }) => {
  const fileName = './audios/' + new Date().getTime() + '.mp3'
  return fs.writeFileAsync(fileName, AudioStream)
    .then(() => fileName)
}