Akira TV Jack Socket

Astarehan -  
 Astarehan -
Good evening, I have a simple problem.
I recently bought an Akira TV (LED-B03TU19H) and I noticed that there is a jack plug at the back. I tried connecting my Beats headphones, but the sound continued to come from the TV instead of the headphones. Can someone shed some light on this issue? I read in a few forums that it might be due to the type (Digital/Analog), but it's still unclear to me.
Could it be because of the HDMI? (it enhances both the image AND the sound, right?)