Wow, I've had to do a research proposal like that but not had to actually carry it out. That's intense. Since asked about something fun, music does seem to be cool. I don't know if relating it to memory would be so easy to test for. Possibly. You could test something similar by looking at how well someone does academically if they listen to music while studying by surveys. You could also see if people who listen to music while studying are happier than those who don't through a survey. I'm not sure if you need to use tested measures to be valid in this project or not. That becomes more complicated. And then there are variables too because there are different types of music and so the thing you are looking at as a constant is in fact variable. Sorry if this isn't helpful. Just thinking aloud.

You could also broaden it to find out if students with developed outside interest (like hobbies or sports or artist expression) were either happier or did better in school than others. Same for people who had more developed social interests.

I think if I were doing something along those lines, I'd be curious about the effects of social media. Like asking about the number of hours or intensity of involvement and correlate to set of other questions about happiness, number hours with friends doing activities, grades, self-image, etc.