No matter what the language, the speech of women and men differs (to a greater or lesser extent depending on the language, traditional Japanese, for example, being an extreme case), even though all human beings in a homogeneous social group tend to speak like each other. Biological sex is a determinant of speech production, in the first place, because the size of the organs involved in articulation (like the larynx, the oral and thoracic cavities, etc.) are typically larger in men than in women. Women, therefore, normally use a higher register (pitch) than do men to produce speech sounds, although under special circumstances (like falsetto or castrato) men and women are both capable of speaking with uncharacteristically high or low pitch.
In contemporary American English, because of the general tendency among younger women and girls in particular toward apotropaic strategies (the “apotropaic smile” being one such largely unconscious device), the increasingly dominant place of articulation in the buccal cavity is toward the back. This gesture involves retracting the lips and narrowing their aperture, all of which constricts the vocal tract and contributes to the impression of constraint on the hearer that is notably absent in the speech of males of the same age.
As an ensemble with the intonational and vocal timbre peculiarities of contemporary female speech noted in earlier posts, these apotropaisms can only be evaluated as an atavism that runs semiotically athwart––and threatens in part to undermine ––the aims and gains of the women’s movement.