What Makes a Voice Sound Attractive?
Well, according to researchers, an attractive voice reflects an attractive perceived body size.
A group of human subjects listened to the same sentence that was manipulated by altering pitch, acoustic resonance, and voice quality based on body size projections reported for animal calls and emotional human vocal expressions.
For example, a rough, low-frequency animal call suggests the vocalizer is large and aggressive whereas a more clear, higher frequency animal call suggests a small, non-threatening animal.
Not surprisingly, male listeners preferred a female voice that suggested a small body size (relatively high pitch, wide acoustic resonance range, and breathy voice). Think Marilyn Monroe...
Female listeners preferred a male voice that suggested a large body size (low pitch and narrow acoustic resonance range) akin to actor James Earl Jones. However, female listeners interestingly also preferred some breathiness in the male voice which may signal a perceived decrease in the aggressiveness associated with a large body size.
Another reason why patients undergo voice therapy, even if there's nothing medically wrong...
It is not unusual for a male lawyer to undergo voice therapy to try and achieve a lower and more aggressive vocal quality as it does correlate with success. (Read more about this link between voice pitch and success).
Similarly, women in positions of authority in the political and corporate world do the same. Margaret Thatcher underwent voice therapy for this very reason [link].
However, women with a low raspy voice often pursue treatment to try and achieve a more feminine voice (high-pitched and breathy).
Indeed, when voice therapy fails, there are even surgical procedures to try and alter a person's voice.
Voices Considered Attractive Send Body Cues. Scientific American. 4/30/13
Human Vocal Attractiveness as Signaled by Body Size Projection. PLoS ONE 8(4): e62397. doi:10.1371/journal.pone.0062397