What does "voice" mean"? Finding your "voice" in academic writing is similar to choosing what to wear for a particluar occasion. "Voice" means thinking about language markers such as:
1. assertiveness
2. self-identification
3. reiteration
4. authorial autonomy of thought
See Cally Guerin
https://doctoralwriting.wordpress.com/2015/08/30/authorial-voice-or-putting-on-the-ritz/