WhatsApp has just released an update to the private beta version of the app for Windows Phone. This version, 2.12.20 brings ability to send MP3s and a switch for read receipts.
Just like all the other privacy settings in WhatsApp, switching it off for yourself will also stop you from seeing when others read your messages.
– Send MP3 file to sender
– Read receipt toggle
Also FYI, this is only for the private beta version which is currently not available for anyone in the public. So all we can do is wait for the public version to be officially released.