i see this post dates from a while ago.
first thing you must know, is that schyzophrenia as a sickness only exists in the north-american / european societies. they still don't know what it is. they medicate people, and dont really help them.
at age of 14, its hard to say, because teenagers can do lots of stuff they dont let parents know about. perhaps, if they taken drugs (doesnt mean that the voices are heard under drug influence, but drugs "open doors" to other abilities), or if they have been through some emotionnal schocks, or discapointments, or fears. strong emotions can stir the mind.
I was schyzophrenic and quite silent and absent for two years, and with understanding what was happening to me, slowly got back to myself. but most of people see it as a mental desease, and see no exit. schyzophrenics face more cerabral electrical activity, that connects their brains like radios, and connects them to random places. that's one thing. the absences, are usually caused by "tuning in" (now, to understand that, you have to lookup some things that some people call occultism, but that is just a not well known ability. there is also something called "chanelling" that might be happening.
i consider schyzophrenia as an altered state of mind, not a sickness, and your daughter might be very sensitive to emotions surrounding her, energetical vibrations, and might be very receptive to any negative emotion, like a baby in a mother's stomach.
its important, the nature of the voices she hears, if theyre talking to her, or random things.
i know you love your daughter, this is why you have to look beyond what the doctors tell you. a schyzophrenic is not a crazy person, its just more sensitive, telepathic people. if you get help, dont believe in everything they say. stick to your daughter, establish a relationship of confidence, dont overreact, and believe in her. even if what she says might sound crazy, maybe its a metaphor of something she is receiving emotionally as a receptive being. my mom was very supportive when i was schyzophrenic, but i also needed some space, and no pressure. wish i could help more, dont hesitate to ask.