I am aware of that, but I've listened to cheap earphones, I've listened to the newer low-mid-range Apple earphones, I've listened to $70-range earphones, and I've listened to mid-range ($100-200) studio headphones and mid-range ($700-1500/pr) studio monitors, and there's no way that a response curve largely matching $10 earphones (or even $70 earphones) can be described as "superb".

That said, I'm complaining about the article, not the research. By all means, Berkeley researchers, please continue developing graphene earphones!