The voice analysis is very accurate. It's the same as used in another of our apps 'Voice Analyst' which is used by voice therapists/pathologists world wide. It takes a voice reading 50 times a second and at the end of the recording each of those readings is assigned male/neutral/female depending on the hertz value.
The hertz values used to determine male/neutral/female are those used by speech therapists and are generally accepted indicators of voice type. The values are 140Hz and lower is male, 160Hz and above is female and those in between are neutral/gender ambigous.