Using Earpods on PC with TRRS to 2xTRS splitter

I just purchased a 4-pin to 2x3-pin audio adapter to use my earpods on a PC. However when I test the microphone all I can hear is a high pitched noise. The earpods are confirmed working on a retina MBP and android phone (everything works on MBP, mic + centre button works on android phone but no volume control as expected). I have tested a pair of beats in-ear earphones with the new splitter, and they're working perfectly (audio + mic). The beats earphones also work with my MBP. Any ideas on why the earpods don't like my splitter? I'm fairly certain beats and apple use the same CTIA standard.