This variation could be due to the differences between species or genders. A female's wing makes a higher tone than a male's wings. Both male and female mosquitoes have mouth parts, but only a female's is adapted to pierce skin and suck blood. Female mosquitoes only suck blood to develop eggs. In addition, the male's antennae are very hairy while female's antennas have a few small hairs.
Females also live longer than male mosquitoes.