A popular form of hormone replacement therapy (HRT), which is often used to stave off the changes associated with female aging, can accelerate hearing loss. University of Rochester researchers led by Robert D. Frisina found that women who were taking a combination of estrogen and progestin had hearing deficits typically expected in women five to 10 years older. The study of 124 women between the ages of 60 and 86 points to progestin as the culprit, because the hearing of participants who took estrogen alone was unaffected by the treatment.