ufos may use some kind of frequencies that could be herd over a modified ulf-vlf receiver like i get when i experiment with some of the modified parasite zappers ive made i can hear then as like tones or sounds over my headphones which is baffling as the circuits these signals are coming from have no rf type coils or crystals or antennas , the funny thing is when i grab the coper pipe electrode mainly the positive it amplifies , so ive built another modified tens circuit and used ten valued ceramics for more frequencies to see what i get that my receiver can hear and translate to a sound so ufos may be interesting to hear when they are around, heres the frequency emitter , and my receiver, the modified tens circuit emits frenquencies not just from the outputs but also via em waves and i hear them over my receiver .