I hear sounds like explosions or crashes randomly sometimes in my head..never really voices or exact words...sometimes if youre thinking hard enough a concept can seem like a 'voice', like the thought is so strong that it's having a conversation with your conscience but you don't usually actually hear words in one ear or the other...but i wouldnt worry about schizophrenia or anything like that unless the voices are perpetual and deafening and/or controlling decisions you make and actions you take in day to day existance