Masking a woman into a male voice created a slight disadvantage, the other way a slight advantage.
Also, women underperformed men by about 0.5 on the scoring metric before the modulation.
After interviewing 100's of candidates, I realized women are more easily intimidated on average and also need to be much more careful in how they present themselves in interviews. (Some non-trivial percent of interviewers think aggressive males are confident, but aggressive women are combative. The candidate doesn't know if I am such a person when they come into the interview.)
I noticed that, on average, women with scores that match those of men (on my own scoring) significantly outperformed the men when hired.
I settled on adding 0.5 points to the score of every woman I interview (then rounding to a whole number). Also, I champion them if they are borderline in the panel discussion.
Based on the gender ratio and performance of the team I recently helped hire, this works great (when I am the interviewer).
Edit: There was a wonderful article by a VC along these lines. Some other VC bragged that their female founders were all way more competent than their average successful male founders. The first VC pointed out that this was as close as possible to incontrovertible proof that they were holding women to a higher bar before funding them. I can't find a link...