Welcome to Justanswer.com, my name is ***** ***** I will do my best to assist you.
My advice is this.. lets connect the PX22's to your PC. Then, what we want to do is start the sound recorder and see if we can pick up any sound from the microphone on your PX22's. This will let us know if its a hardware fault and your microphone isnt working.. or if this is something t o do with your PS3 settings or network settings blocking your mic from transmitting.
If you dont have a pc or a mac, let me know and we can try and find another way to test the PX22's. Or, once youve had the chance to test get back to me and let me know the outcome, and we can go from there.