I would really have liked to see them check whether the gender-blinding actually worked. Even if someone's voice is modulated, they may have gendered behavior patterns that could influence someone's performance ratings. I wouldn't be surprised if I could guess the gender of a voice-modulated person pretty accurately from other cues. To combat this, they could have asked the interviewer during the performance assessme…
Aline from interviewing.io here. Great idea!
That way, you would be isolating the thing you are testing to just the voice, and you would be able to establish controls and a baseline for the exact same interview.
The way your test is described right now, there are still way too many factors that could explain the results. Your controls are far too loose.