GaAs/AlGaAs Lab

Hello, I am a junior undergrad taking an advanced senior/1st yr grad lab. I've been having some difficulty with a few points in the lab materials we were given (we are analyzing the reflectance spectra for GaAs/AlGaAs quantum wells). We were given the effective mass of the electrons, heavy and light holes. I understand where the effective mass for the electron comes from, but I am not exactly sure where the holes are given mass. It is my understanding that these holes are simply gaps left when electrons move from one state to another (i.e. from the valence band to the conduction band). Is the mass of the hole in some way related to the energy emitted/absorbed in this process?