If you're standing next to a jet during takeoff, you eardrums will probably burst. Same thing happens when you fire a 12-gauge shotgun right next to your ear. When we're exposed to exceptionally loud noises, something called the stereocilia
in our ears gets damaged. This causes our ears to mistakenly send signals to our auditory nerve cells and the resulting ghostly reverberations are what we call ringing ears. Most of us have probably experienced it possibly from going to a really loud concert. The technical term for it is tinnitus
and it's usually temporary unless you repeatedly damage your ears with loud noises -then it develops into chronic tinnitus when you hear that dull ringing for the rest of your life. However, it's nothing compared to what a really loud noise can do to you.
Noise can actually kill you. Sound travels in waves and when they enter our ear canals, they make our drums vibrate and if they're too strong, they can snap the cells inside. To avoid this, we use units called decibels to measure the power of sound. Anything below 85 decibels is thought to be safe, but at 150 decibels, your eardrums will burst. At 200 decibels, your lungs will rupture and likely kill you. Therefore, the threshold for death by sound is somewhere 185-200 and is due to air pressure caused by acoustic energy. This has happened during wars when high energy impulse noise from explosions caused something called blast overpressure. It leaves no external injuries but damages organs like your ears, your lungs and your gastrointestinal tract. Acoustic weapons are actually being developed, but usually, they're for non-lethal purposes. However, here is one device that would most definitely kill you with sound.
It's not a weapon, but a huge air horn developed by the European Space Agency which was used to test satellites and spacecraft. Using nitrogen gas to produce sounds up to 154 decibels, they blast objects to make sure they can withstand the noise of a rocket launcher. The ESA themselves are so concerned about how lethal this horn is, they have surrounded it with a half meter thick wall made of steel reinforced concrete coated with an epoxy resin to reflect noise back into its chamber. Even though 154 decibels are believed to be non-lethal, the ESA believe that prolonged exposure to the 154 decibel horn will kill you as well by rupturing your intestines.