A number of people have asked where the music is stored. It's stored on a regular USB thumb drive. This is to make it easy for a caregiver to change the set of music from time to time. And to make it even easier, the thumb drive is externally accessible. Caregivers generally seem pleased with this approach. An earlier version stored music on a micro SD card (alongside the OS), which is the cheapest way to go. But I reasoned that most people aren't used to working with micro SD cards, so I changed to the USB thumb drive approach.