Interesting. There's an old lady in a home that I know, and she does and says nothing all day, and looks vacant and mindless. But when they played Bob Marley's "Jamming", she sang all the words and grooved and gyrated like a teenager.
All decent care homes use music therapy and bring out objects from yesteryear to encourage people to talk about their past. It's a tough job to work with people with dementia and similar conditions but it can be rewarding.