When faced with life as a sharecropper, a young girl decides to run away and pursue her dream of becoming a musician.

Don't have your logline assume that being a musician is the "most difficult" thing to accomplish. She can always work in the music industry and be a musician, just not on the level as say Beyonce or someone famous -- add famous into the logline -- that may help.

Let's say you add in that she is a sharecropper and is also DEAF -- now, you've staked up the obstacle with a simple disability.

A deaf woman runs away from.... to become a musician.

Now, everything we need to know about this task of hers is front and center. How can she overcome those immense odds?

A powerfully motivating event would strengthen the story.
Is there something that happened to the girl that motivated her to leave?

Hollyweird has a fondness for rags-to-riches, farm-to-fame stories, but as Richiev noted, so many have already been done that in order to get attention this logline needs to ?pitch a story that has a new angle, a ?unique twist. ?A plus factor would be if it's a biopic.

Please, more story detail.

This is still just set-up, the story would be what she must do to become a musician (Soul Singer)

Also, because there are many stories about a small town girl heading to the city to make it big...
you need to add the element in your script that sets apart your story from the rest.