windows phones 8.1 audio settings not working

[Navaneeth vijay]

the audio app in the settings list doesn't show equalizer option ! it disappears within a second after I open in lumia 520
::straight::eck:

 

[jmerrey]

only works with headphones

 

[Lucas Nask]

I have a Lumia 520 too. This function didn't work even If connect headphones.