Most simple example I could find for ongoing listening of microphone using the google cloud speech api.

stream-speech.js

// Imports the Google Cloud client library
const speech = require('@google-cloud/speech')
const record = require('node-record-lpcm16')

const client = new speech.SpeechClient({
  // generated service key downloaded from cloud console
  credentials: require('./admin-key.json') 
})
 
const sampleRateHertz = 16000
 
record
  .start({
    sampleRateHertz: sampleRateHertz,
    threshold: 0,
    verbose: false,
    recordProgram: 'rec'
    // Other options, see https://www.npmjs.com/package/node-record-lpcm16#options
  })
  .on('error', console.error)
  .pipe(client
    .streamingRecognize({
      interimResults: true,
      config: {
        encoding: 'LINEAR16',
        sampleRateHertz,
        languageCode: 'sv-SE',
      },
    })
    .on('error', console.error)
    .on('data', data =>
      process.stdout.write(
        data.results[0] && data.results[0].alternatives[0]
          ? `Transcription: ${data.results[0].alternatives[0].transcript}\n`
          : `\n\nReached transcription time limit, press Ctrl+C\n`
      )
    ))