Why does Parvana have to hide her face and voice when she goes to the market with her fahter?

Parvana has to hide her face and voice when she goes to the market with her father to protect herself from potential harassment and danger in a society where women are not allowed to show themselves in public. By disguising herself as a boy, she can navigate the marketplace more freely and help her family without drawing unwanted attention. This act of concealment highlights the oppressive restrictions placed on women in her environment.