I'm making a Speech to Text app and i want it distinguish each human voice. Is that possible?
NO !! speech recognition or ASR cant help you differentiate between two people voices. you need to study about DSP(Digital Signal Processing) technology to do that.
DSP processing is so heavy for a mobile device and normally its done using servers the proper way to achieve this is sending the recorded voice to the server and processing it.
voice recognition will just help you to recognize the words while speaker recognition will help you to realize the speaker. google "speaker recognition". there is also a tool called ALIZE that does this.