Lack of females in "difficult" music scenes is very noticeable, both as artists and as audience. I think part of it is innate preferences and differences between the two sexes. Despite equal opportunities, choosing different things. For example women have very little interest in some film genres such as War, Action, Western, Science Fiction films. Films that feature lots of male violence, it simply doesn't interest them but men seem to like those. Similar to styles of music that contain lots of abstraction, noise included or disciplines that contain abstraction such as Mathematics and Philosophy leave them indifferent for the most part.
Part of it is cultural, the culture that rose from the ashes of the destructive two world wars, they blame masculinity for the violence and destruction in the world. Male interests and displays of overt masculinity are seen as problematic and not socially acceptable. Men though, still needed an outlet for the supressed masculinity hence you have thriving male dominated subcultures such as noise/PE and metal. In metal as well, there aren't many females, is mostly an outlet for men to feel like glorious warriors of the past.
