...in an attempt to overcome biases in hiring, most orchestras changed their audition policy, and began using screens to conceal the identity of the candidate.
Female musicians in the top five US symphony orchestras rose from 5% in the 1970s to around 25%. This could have been due to wider societal shifts, so Goldin and Rouse conducted a very elegant study, Orchestrating Impartality: they compared the number of women being hired at auditions with and without screens, and found women were several times more likely to be hired when nobody could see that they were a woman
Via Stallman.org