This is particularly interesting to me as I can't seem to find any information on the topic, but, having listened to numerous Polish speakers from both sexes, the male─female pronounciational split is very distinctive to my Russian ears.
In particular, here are some differences that I have observed:
- Palatalisation. Women tend to palatalise their soft consonants (and so most often pronounce e.g. "wiedzieć" as [vʲedzʲetsʲ] or [vʲeɟec]), while men keep the consonants hard but add a short "i" or "j" sound after "b", "p", "m", "w", "f", "g", or "k" or palatalise the consonants completely to turn them into hushing sounds in cases of "ś", "ź", "ć", or "dź" (and so most often pronounce "wiedzieć" as [wjedʑetɕ] or [wiedʑetɕ]). For example, compare this male voice with this female voice.
- Nasalisation. Men tend to nasalise their "ę"s and "ą"s before sibilants and sometimes at the end of words or pronounce them as [ɛw̃], [ɔw̃] or [ɛw], [ɔw], while women tend to replace them with [ɛn], [ɛm], or [ɛ] and [ɔm] more often. I have found this rule to be less consistent than others.
- The letter ł. Women tend to raise their tongue when pronouncing this letter, so that it sounds closer to an [ɫ], while men tend to pronounce it as a clear [w]. For example, compare this female voice this male voice.
I believe there are other differences, such as vowel reduction and vowel fronting, but I wanted to keep this question short and concise, so I only went through the main differences that I have observed.
I have known a few languages other than Polish throughout my lifetime, which include Russian, English, French, Greek, and Hebrew, but in none of them have I observed any consistent difference between male and female speakers. Why is it that Polish has this interesting feature? Are the reasons psychological, biological, cultural, or some combination of these?