Change voice during phone call android

Question

I want to make an android application that allow user change the voice during phone call. For example: You are a man, you can change the voice to a woman or robot when talking o

Answer 1

Hard way

You get the input voice, you use voice recognition to detect the words, then you use speech-to-text with your desired voice as output.

Less hard way

Sound processing: Changing frequencies, amplitude etc.