According to an article on the Scientific American blog, a lower pitched voice is normally associated with a more masculine, taller and attractive man. Research has shown that women in North America prefer deeper-voiced men as short term partners, and research on the Hazda people of Tanzania has shown that men with lower timbre and pitched vocals have more living offspring. However, that might be because lower pitched men are getting selected more by the ladies, and have more chances to procreate.
For the study, published in the Dec. 22 issue of the journal PLoS One, researchers made voice recordings of 54 heterosexual Australian males 18 to 32 years of age. A semen analysis showed that sperm from deeper voiced males scored lower on seven “motility parameters,” meaning the sperm were less likely to link up with an egg. This effect has been seen in dominant males throughout the animal kingdom, from artic charr to cockroaches, according to the researchers. The more attractive the male gets, the lower his sperm quality.