If you are using Safari when editing your Yodel settings on your manage.yodel.io interface, you may experience that audio files are not played. 

Please go to Safari --> Settings for This Website. 

Safari Settings for manage.yodel.io

A new window will pop up in the middle of your screen. Navigate to the settings for "Audio-Play". Click on it and select the first option, which says "Allow All Audio-Play". 

Allow All Auto-Play in Safari

All audio files can now be listened to on your manage.yodel.io interface.