Could it be something to do with the type of connector you have on the headphones compared to the S4? See ... 3.5 mm jacks: 4 vs 3 conductors ... pretty picture at the bottom. Also see here ... Digital iVision Labs!: How Do 3.5mm Jacks (TRS Connectors) Works? .... and here ... Adapter for Nuforce NE700M for Nokia Xpress Music 5310 ....

Maybe those links will shed some light ...

Dave

 

Disregard what's in the notification bar. Have you tried using the mic to record?

 

Take a look at these two threads as we have no idea what sort of connector your mic has. See ... Audio Recording With a Smartphone - Wild Mountain Echoes ... and ... External Mics on Galaxy Devices Just One Resistor Away - XDA Forums ...

With all these links I'm sure you can figure a way to do this either with your current mic or some other with the right connector/app.

Dave