Because of the way iOS sandboxes each app (and therefore each app has it own file store), let us know what app the files in question are in.
Generally to the iPad, you can use the file transfer feature in iTunes on you PC/Mac. This is under the Apps tab of the device when connected.
From the iPad to PC/Mac will spend on the app. Dropbox is a good intermediary if the app in question supports it.
In regards to audio, are these specifically music in your Music app? If downloaded from the iTunes store directly to your iPad, these will sync to your iTunes library when you sync your device.