When Meg Ryan demonstrated just how effortlessly a woman could fake an orgasm in When Harry Met Sally, co-star Billy Crystal was not only embarrassed, but stunned.
Now it appears there may be some truth to the idea, as a new study has shown that the noise a woman might make in bed does not often correspond with her orgasm.
According to research from the University of Central Lancashire, a woman's 'copulatory vocalisations' are made most often before her climax or during her partner's.
The findings were based on analysis of 71 women with an average age of 22. The study aimed to identify whether a woman's vocal expressions during intercourse were triggered by orgasm or occurred independently.
Each participant completed a questionnaire about their sexual behaviour, which included details about how they reached climax and at which point they were most likely to express themselves vocally.
Most women polled said they reached orgasm during foreplay, but were most likely to vocalise their enjoyment during their partner's. The researchers believe the reason for this discrepancy is that women are 'manipulating male behaviour to their advantage'.
They wrote: 'These data together clearly demonstrate a dissociation of the timing of women experiencing orgasm and making copulatory vocalisations 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 behaviour to their advantage.'
Another suggestion is that women are conforming to 'an idealised sexual script'. Dr John Grohol, founder of website Psych Central, commented: 'Women appear to vocalize during sex not to express their own enjoyment so much as to help the man reach climax.
'Maybe these vocalizations are a part of that idealized sexual script, or at least done in response to what women believe their male partner wants.'