You would need to go into your music player and change its 'settings' to locate files on the card. They are normally set to search the phones internal storage unless you make that change.
The same goes for using system sounds. You would need to change the 'settings' to search the card for sounds.
When you tap the Music icon in the Apps list, it should play any music wherever it's stored in the device. Alternatively, find the files and tap one and it wll cause the Music App to start working.
You would need to go into your music player and change its 'settings' to locate files on the card. They are normally set to search the phones internal storage unless you make that change.
The same goes for using system sounds. You would need to change the 'settings' to search the card for sounds.