People spend a lot of time talking and thinking about how members of the opposite sex look, but very little time paying attention to how they sound. To our unconscious minds, however, voice is very important. Our genus Homo has been evolving for a couple million years. Brain evolution happens over many thousands or millions of years, but we’ve lived in civilized society for less than 1 percent of that time. That means that though we may pack our heads full of 21st century knowledge, the organ inside our skull is still a Stone-Age brain. We think of ourselves as a civilized species, but our brains are designed to meet the challenges of an earlier era. Among birds and many other animals voice seems to play a great role in meeting one of those demands — reproduction — and it seems to be similarly important in humans.
Check this interesting article about the importance of voice here: Voice