Age-related hearing loss
Hearing naturally deteriorates as people get older, a process for which the posh word is 'presbyacusis', but the way I think of it is that there is direct correlation between the more you grunt when you sit down and the worse your hearing will be getting.
When we are born we have a bundle of sensory cells in the cochlea within our ears, and this number is fixed. However many were there on the day you were born is how many you have for life, and when they get damaged or stop working then that's it, that cell is out of action for life now.
Up to your late teens and early 20s there is usually no noticeable deterioration in hearing, but from then on the losses start. In some people the deterioraton may be fast, while in others glacially slowly, but changes do start to happen. Often it is the very highest frequencies which go first, meaning teenagers can hear really high pitched noises that young adults already can't. This has been put to use in some shopping centres where they use a 'mosquito' device which plays a sound teenagers can hear and which is annoying so they move on, but to anyone else it's just not there.
Eventually these high-frequency losses start to come down the frequency range and enter the zone where normal day to day sounds are heard, including speech and music. The best way to describe it is that overall volume doesn't fall off much, not yet anyway, but the clarity and sharpness of sounds starts to get a little mushy and things get a little indistinct.
As the years progress, there is a difference between men and women, with women generally having a better standard of hearing than men, with the gap between the two growing as the years progress. Women's hearing does deteriorate as well, just not as fast as a chap's. At the age of 65 a woman could have lost about 58dB of hearing at the important 4kHz frequency, while a bloke could have lost 70dB. Remember, 3dB is doubling the power of the noise so a gap of 12dB is very big.
This is why, in the audiometry screening tests, both age and gender are important as we need to compare the attendee's result not against so-called perfect hearing, but against what is normal hearing for their age.
Why is there a gender difference?
This is my guesswork and supposition rather than something I've read elsewhere, so read it in that light.
There is no physical difference in the structure of the ear between a woman and a man, they are exactly the same and respond to noise in exactly the same way, so why should women's hearing not deteriorate at the same rate as men's.
My thought is that the expected standards for age and gender are based on decades of research and data and this is what has been used to create the standards. But, those 'normal' standard have to include hearing loss due not only to age but to average lifestyle and average working exposures as well, and going back it was far more common for men to be working in heavy noisy industries than women, therefore it would be logical that those additional losses due to that increased exposure are built into the 'normal' standards.
Given that, it would seem most likely that the normal standards of hearing for women are actually the correct ones for both genders and are closer to natural losses through age.