You’re better off looking at their physical build than by voice when determining sex.
Females tend to be short and squat in their neck compared to ganders. Ganders will also instinctively get between you and who they’ve bonded themselves to, which can be a goose or another gander.
After their first winter, that’s about when their voices become fully mature. Mind you though, different individuals have different voices, one gander won’t sound like another and one goose won’t sound like another.
The best way to tell though is that girls tend to do a alert/ war cackle that...