Can't hear voice from my Macbook

Well, first, I can't hear sound from my Output (only from headphones), I already tried to insert the headphone 20 times, reboot, reboot audio files, put something into the headphone plug. Nothing worked

And now, even on my headphone, audio is not coming right. I CAN'T HEAR VOICES!

On a music for exemple, I can hear all the Instrumental, but not the Vocal =O

Someone knows how to make it work right?