One of my potential research areas, when I was working on my M.S. in Computer Science, was data sonification. There’s so much information on data visualization, and it is a tool that is used in so many industries. But there seems to be a lot less interest in data sonification. While I admit that the use cases are more limited, I think there’s still plenty of research that can be done.
For one thing, time series data may be more usefully encoded, at least in some cases, as sound, rather than a visualization.