hmmm honestly it only takes the understanding of what frequency can be used in which species and technically its quite painful since I had surgery on my ears at a young age ( I was born deaf ) I currently have issues with tons of sounds at once too much noise and certain sounds and noises make my ears hurt or make my chronic head aches turn into untolerable migraines but I do have a decent pain tolerance otherwise hearing whistles would be dreadfully painful.... I wont lie if you use the right frequency you can even use white noise or certain sounds to reprogram the human brain since the brain is like a organic computer it unfortunately also can be hacked but not like normal computers you must know the right code or frequency