I guess you'd know if a buck would travel in a herd of does where you live, but here they are often seen with a grouping of does between the different rut cycles and especially following rut.

Does also grunt so it could be a doe barking (actually) grunting to her fawn or other doe(s).

I have heard loud grunts produced by both buck and does, but like you most are of softer toned nature. Sorry can't really say for certain, good luck getting your deer .