Does anyone know what the hyper- prefix here signifies? These diagrams remind me of microphone response graphs, and there's a type of microphone called hypercardioid that resembles this shape.
I don't know for sure, but I generally expect "hyper" in mathematics to mean "extended into an extra dimension".
A Hypercube is a 4-dimensional cube. A hypergraph is a graph with 3 (or more) vertices per edge, instead 2-vertices. Finally, a "Hypercardioid" is a cardioid, except in 3 dimensions (instead of the typical 2-dimensions).
