Infrasound is actual silent, at least humans cannot hear it as it is the sound that is below the range of human hearings. However, it is finding increasing use in Horror movies, where directors have realized its potential to provide an even scarier effect. You see infrasound has the uncanny effect of freaking us out: even though we cannot hear it we do feel it.
Horror movies rely heavily on setting the scene with the aid of music, generally speaking, a horror movie production will have a whole team of composers carefully deciding how they can increase the impact of the scene by using music. Sometimes familiar sounds will be distorted to give us that eerie feeling or to make us believe reality is not as it seems.
But the real winner is a hidden sound that really freaks out the audience, a technique that many filmmakers will use to add to the scene. A low-frequency sound that cannot be heard but unsettled every human being down to their very bones. Infrasound only exists at frequencies lower than 19 Hz, which is a sound we can feel but not hear. And this is a sound that does exist naturally also we find it created by the wind, earthquakes, avalanches or even elephants who use it to communicate. And horror movie composers like to use this sound to their advantage.
Horror and thriller movie director Gaspar Noe has noted that you cannot hear many of sounds that he puts into his films, but it still will make you shake. If the theater has a good sound system then he feels you can be more scared by the sound than what is actually what is happening on the screen. Deep rumblings and otherworldly grinding sounds are perfect for scaring us and raising anxiety.
Scientifically speaking infrasound has been proven to induce anxiety, heart palpitations, and shivering. Definitely, an amazing technique that horror directors are making use of around the world, so the next time you go to see your favorite horror film make sure you are going to the good quality theater – as it seems that is the best experience!