OpenSL ES is initialized, but the only thing coming out of speakers yet is silence! So what about finding a nice piece of music (sometimes abbreviated BGM) and playing it natively with Android NDK? OpenSL ES provides the necessary stuff to read music files such as MP3s.
Project DroidBlaster_Part7-1 can be used as a starting point for this part. The resulting project is provided with this book under the name DroidBlaster_Part7-2.