Why is the sound missing in responses that are submitted through a phone?

Typically the reason why the sound may be missing when people submit responses through a

phone is because they need to enable their browser to use the phone’s microphone. 

iPhone (Safari)

To give Safari access to your microphone, you can simply go into your phone settings > Privacy > Microphone > switch Safari ON.

Android (Chrome)

On your Android device, open the Chrome app. To the right of the address bar, tap More > Settings > Site Settings > Microphone. Tap to turn the microphone or camera on or off.

If you see Boast under Blocked, tap the site and then “Access your microphone” and then “Allow”.