Edge Browser: Try saying Revelation 21, Revelation chapter 21, or Revelation chapter 21 verse 4.
Chrome Browser: Try saying Revelation 21, Revelation chapter 21, Revelation chapter 21 verse 4, and possibly Revelation 21 4.
Safari Browser: Try saying Revelation chapter 21, Revelation chapter 21 verse 4.
Voice recogntion is not supported in Firefox.
https://locatescripturebyvoice.iamwarren.us
https://warrenkc.github.io/locate-scripture-by-voice-recognition
https://github.com/warrenkc/locate-scripture-by-voice-recognition