Check "Manage Bluetooth devices" under accessory settings just to make sure that your playstation is detecting your Bluetooth headset, then check to make sure that under audio device setting the microphone level is adjusted correctly and it's picking up your voice when you speak. Obviously make sure that your input device is your headset. If that's all good and out of the equation as to what can be wrong, go to options in Battlefield 4 and make sure VOIP is on under the audio tab so you are able to speak to your squad.
I hope this helps, it worked for me so this is why I added my input!
