"Female voices are significantly deeper today than they were years ago." http://www.tagesspiegel.de/wissen/neue-studie-die-weibliche-stimme-ist-tiefer-geworden/20813946.html …pic.twitter.com/tkP0K7RA6i
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According to the German media, this is based on a congress lecture, couldn't yet find a published paper. I have my doubts too.