Leaked audio of Britney Spears' 'Toxic' without the Auto-Tune may surprise you.

Britney's natural singing ability has always been debated, but after hearing her raw vocals on the 2003 pop hit we're wondering why they even put the auto-tune treatment on her voice in the first place?

In case you forgot what the final studio version of 'Toxic' sounded like, just check the video below.

How do you think the two versions compare?

[via YouTube]