I read somewhere that it is easier for babies in utero to hear low voices (like dad) rather than higher voices. Not sure if that's true, but I wonder if that's your LO is sometimes more responsive to dad?
We've been playing music for LO...sometimes it seems like she stops to listen, then moves around after the music is done. Except for Beethoven...she seemed to be moving in time to the 7th symphony the whole time (which has lots of low-register drum movements, etc.).