Hii, I have read your requirement and ready to discuss this project.
I am a Senior Android Developer with extensive knowledge of Android SDK, latest trends and technologies and developed many applications so far that are also live on Google Play Store.
I have worked on many apps that are using geofencing even I have done my final year project with containing Geofencing for multiple users entry and exits. Yes we can play audio file on entering to Geofence for a particular location.
You may contact me any time for this project with satisfactory result. Looking forward for your positive response on my bid.