John Krasinski's A Quiet Place is one of the best monster movies in years, and this is because not only is the family drama at the heart of the story incredibly compelling, but because the monsters themselves have such a specific and unique gimmick: they hunt via sound, and they do it very efficiently. But how exactly do they hunt? How is their hearing so good? Does anything in nature have similar kinds of hearing we could point to? We don't have an exact answer--the movie is vague on purpose--but we have enough evidence to make an educated guess.
Spoiler Warning! This post will spoil certain scenes and moments from A Quiet Place in order to examine how its monsters hunt. We highly recommend you go see the movie (because it's great, first of all) before continuing, unless you're a-okay with being spoiled. You've been warned!
The monsters in A Quiet Place have sort of insectoid-humanoid physicality, and we know they're upsettingly fast, but the way they track prey has a lot more to do with birds and flying mammals. Several times in the movie, we see close-ups of their massive, giant ear canals which can hear in all directions. This is very like the way owls hear and hunt.
Owls have big giant ear holes, which we can't usually see because they're located under and between their heavy layers of feathers. Owls ears are also at different levels on the side of their head (see image above). This is so an owl can pinpoint not only if the sound is coming from the left or the right, but whether it's coming from above them or below them. This allows owls to hear across great distances and even underneath the snow.
The shape of the owl's head and face are also enormously helpful in hearing quiet sounds from quite a long way a way. The barn owl and the great grey owl, for example, both have dish-like face feathers, which work the same way putting a cone around your ear works, or omni-directional microphones do. This allows them to hunt for tiny little animals that generally don't make sound any other animals can or would be able to hear.
The monsters in A Quiet Place not only have these massive, owl-like ear canals, but their heads open up into flaps which can collect sound. This is also very owl like, but unlike owls, the monsters' flaps can move in multiple directions (and they have like five of them) at the same time, to gather sound from all around them. This is much more similar to the massive ears of another night time hunter, the bat.
The above picture is of a Pallid bat, which has massive ears, but all hunting bats have similar ears. The conical, scoop shape of the ears help pull sounds from all over into the bat's ear canal. The monsters do this same thing, though with five flaps, they can pull in sounds from much further away. Between the massive, offset ears and the sound-scoop flaps, the monsters could essentially hear things in 360 degrees from any point in three-dimensional space. But they have one other tool that helps them, but also leads to their downfall.
Bats famously use echolocation to help find prey. Because they hunt in the dark, bats need help getting the lay of the land. They send out ultrasonic sounds that bounce off of trees, rocks, or preferably prey, which bounces back and is picked up in the bat's massive ears, which helps them pinpoint location. Ultrasonic sounds are sounds too high for human ears to pick up. Other animals, such as elephants and whales, make what are called infrasonic sounds, or sounds too low for human ears to pick up.
Unlike bats, however, the monsters actually are blind. There is evidence in A Quiet Place that the monsters emit some kind of sound frequency to help them hunt things. We see when the monsters come into the family's house, and Emily Blunt and the children stay put and stay as quiet as they can, the monsters make little clicking/chirping noises, presumably for echolocation. Its ear holes hear things at great distance, and its flaps pinpoint direction, but it's the echolocation that can help them find the prey in close quarters.
The biggest plot point in the altercation is when the monsters set off the daughter's hearing aid her father made for her. We can put together that the monster sounds are feeding back in the hearing aid, which is made out of speaker bits and resonators. The hearing aid is essentially a microphone and focused amplifier, and it is able to pick up on the high frequency noises made by the monsters. This feedback hurts the monsters, and later amplifying that feedback ends up sending their sensors into a tailspin, and their flaps go insane, which allows Blunt's character to shoot a shotgun at their soft inner brain. It's a particular sound that leads to their downfall.
Anything that can hunt like an owl and a bat is bound to be one of the most formidable predators in the world, which the monsters in A Quiet Place definitely are. But the same thing that makes them so effective is exactly what makes them vulnerable.
Images: Paramount/BBC/National Geographic/ScienceABC