Evidence to Suggest that Copulatory Vocalizations in Women Are Not a Reflexive Consequence of Orgasm.
-- Brewer G, Hendrie CA. Arch Sex Behav. 2010 May 18.

.. The studies revealed that orgasm was most frequently reported by women following self-manipulation of the clitoris, manipulation by the partner, oral sex delivered to the woman by a man, and least frequently during vaginal penetration. More detailed examination of responses during intercourse revealed that, while female orgasms were most commonly experienced during foreplay, copulatory vocalizations were reported to be made most often before and simultaneously with male ejaculation. These data together clearly demonstrate a dissociation of the timing of women experiencing orgasm and making copulatory vocalizations and indicate that there is at least an element of these responses that are under conscious control, providing women with an opportunity to manipulate male behavior to their advantage.