To use custom push sounds you must add the sound files you wish to play to your project as a resource. Sound files need to be located in the "res/raw" directory of the app.
You can then use these sounds when creating a push notification campaign on the platform All that needs to be passed in on the platform side is the name of the file. So if I wanted to play file with the path of "res/raw/gong.m
To use custom push sounds you must add the sound files you wish to play to your project as a non-localized resource of the application bundle as shown below. For more on bundle structure see Apple's Bundle Programming Guide
You can then use these sounds in your app home when creating a campaign. You simply enter the file name under sound on the iOS Channel screen as shown below. The audio data can be packaged in an aiff, wav, or caf file and for more on preparing custom alert sounds see Apple's Local and Push Notification Programming Guide.
The sound field is found on the platform page in some versions of Xtremepush