Interesting one. I have no education in music, but I'd try substituting something meaningful for the Tas and Titis. Maybe they could do it better with Yes and NoNo, or Mom and Daddy, or something less abstract? I've run into that with short-term or working memory capacity - an adult can recall 7 (+/- 2) things that make sense, like a seven-digit number. Little kids don't do too well with digits, but can remember 7 +/- 2 little animal pictures. My thinking is that they have nothing to "hang" tas and titis on, so they are thinking about the tas and titis, not about the task. Let me know if it works, it's an idea, not an experience!