Aww, some people sign with their real name at the bottom of the post 😛
You can mess with more of the settings in Audio MIDI Setup app (Apps>Utilties Folder). Perhaps changing the frequency or enabling the hardware rate converter will get rid of the high frequency pitch. Hope that helps.
EDIT: I just had another thought was well, if the mic cable isn't shielded it might be picking up electronic/electrcal interference so make sure it isn't crossing over/touching any other cables.