Can Cocoon detect ghosts in your home this Halloween?

There are many theories about what causes ghostly hauntings. Are there spirits stuck between this world and the next? Or are ghosts simply a figment of our superstitious imaginations? Whatever you believe, there is one scientific theory that fits with many ghostly sightings. If correct it could mean that Cocoon home security system, like an actual Ghostbuster, could catch any ghouls haunting your home!

Have you heard of the “fear-frequency”?

Humans hear within a narrow band of sound. Within that range of 20 Hz to 20,000 Hz exists beautiful music, the voices of your loved ones and the blasting sounds of jet engines. The sounds of life exist in this range, but below that range exists infrasound, dead sounds, vibrations in the air below 20 Hz that are so strange that the human ear can’t detect them.

Infrasound is the frequency of sound that Cocoon home security uses to detect intruders in your home. Eerie sound waves vibrating just below the human range of hearing, within certain ranges of infrasound, are said to exist within the fear-frequency.

For as long as there have been people there have been reports of supernatural sightings and sounds. Ghost stories designed to scare children, but perhaps there is some truth in the ghoulish moans heard in the dead of night, or the creaking floorboards in old draughty houses. Just below the range of human hearing, and just inside the range of Cocoon’s hearing, at 18.9 Hz the fear-frequency starts to make itself felt.

Exposure to this frequency can induce feelings of anxiety, especially over a prolonged period of time or high intensity. Those bumps in the night, and that ‘something’ seen out of the corner of your eye on the stairs, might be something slightly more sinister. (Or maybe not).

Can sound make us see ghosts?

Boom! Crack! Thump! Movement and impact cause atoms in the air to vibrate, with different vibrations creating a range of sound waves. The frequency of a particular sound wave can have a curious effect on objects and even animals in nature. Glasses smashing from terrible singing in comedies may seem like a joke, but if the voice hits a frequency of around 550 Hz playing it loud enough (over 100 dB – for comparison, Cocoon’s built-in siren is 90+ dB) the sound waves vibrate the atoms in the glass so violently that it eventually cracks apart. This means that singing can break glass! (if the voice is loud enough and hitting the right note.)

Similarly, the fear-frequency is at the right range to make the human eyeball vibrate. Luckily this doesn’t cause our eyes to smash, as in the glass example, but it can make us see things. Blurred shapes and shadows that may or may not exist. Combine this with the proven fact that we feel fearful at the same range of sound and it’s not surprising that vibrations of a certain range could explain why some of us, throughout the years, see ghosts.

Cocoon might be able to sense supernatural hauntings

How Cocoon home security detects ghosts and ghouls

Cocoon’s unique Subsound® technology allows Cocoon home security systems to protect multiple rooms without the need for sensors on your doors and windows. As the movement in your  home generates vibrations in the air, Cocoon picks up those sounds to detect intruders, even if they are in another room. It’s what sets Cocoon apart from other home security systems, and why our customers trust us to protect their homes.

The way Cocoon provides multi-room protection is also how it might be able to sense ghosts. By detecting infrasound, those sound waves below the levels of human hearing sitting in the “fear-frequency”, as they vibrate through the air of your home.

So there you have it. Cocoon isn’t just home security without the hassle, it could also be a smart ghost hunting camera. Happy Halloween!

P.S. Stay safe while trick or treating with Cocoon’s top 5 ways to boost your home security this Halloween.

Things That Go ‘Bump’ In The Night

Ever wondered how Cocoon reacts to the noises in your home? Well, in a very similar way to the way you do.

Things that go bump in the night

Imagine for a second that you’re lying awake in bed and you hear a noise, what do you do? Well, firstly it depends how familiar you are with your surroundings and if you think anyone should be moving around at that time? If so, you may not be worried at all and drift calmly back to sleep.

If, however, you think the house should be empty, you’ll pay more attention. But you probably won’t jump out of bed to investigate just one bump (unless it’s a really loud noise!). Instead, you’ll listen a little more. If the noises are unusual, you’ll worry more and more until you take action. You’ll be particularly worried if you hear a noise which you think never occurs in an empty house – perhaps that squeaking floorboard on the stairs?

Cocoon thinks and reacts very similarly to the way you do.


Cocoon’s microphone picks up a range of sounds in your home, passing them through a signal processing pipeline. This pipeline then filters out higher frequency noise to give emphasis to the low-frequency infrasound that is inaudible to the human ear. The low-frequency sound is then analysed and given a ‘fingerprint’ so that Cocoon can compare sounds occur in the future and determine how similar they are.


Once your family have installed the Cocoon app on their phones your Cocoon will start to understand who should be in the house, who comes and who goes. This means that your Cocoon knows when your house should be empty and Cocoon can learn which infra-noises are usual in your empty house, and which are not.


Since Cocoon has an idea of which sounds are similar to each other, and which sounds are usual in your particular empty house, Cocoon can determine which sounds are unusual. Your Cocoon might worry a bit about most sounds, but it worries most about those associated with people moving in your house.

If there’s no activity for a while, Cocoon relaxes, but a short burst of worrying activity will be enough to spur it into action and contact you.


When your Cocoon gets in touch with you, it’s time for you to take charge, see what is going on (and what was going on in the build-up to the alert) and decide what action you want to take!

John leads the Cocoon Software Development team behind Subsound™ and plays with hula-hoops in his spare time! If you have any questions about anything you’ve read here let us know in the comments!

Sensing intruders through closed doors

We have been working with our cocoon development systems for a while. These powerful little devices are packed with a variety of sensors. One of the useful things we can do with them is to detect infrasound.

Infrasound is another term for low-frequency sound waves. Basically a note so low you can’t hear it (perhaps in the 0-20Hz range). They are useful to us because they are generated by any significantly-sized body moving in air (e.g. a human walking or a door opening) and also because of they way they move around a house.

When any wave fits through a gap it will spread out a bit, just like waves of the sea around rocks:


How much it spreads out depends on the wavelength of the wave compared to the size of the gap. The bigger the wavelength, the more it will spread out. Very low frequency waves, such as infrasound, will spread out a lot. In effect this allows them to be transmitted around a building much more easily than the higher frequency sound we can hear.

For Cocoon, this means that we can detect things such as a door opening and human movement from another room in the same house – the waves generated travel around the house and through even the tiniest gaps beneath closed doors to our sensors.  We can process the infrasound signature in real time and use that as part of the input in our decision making process – deciding if there is something going on at home that you would like to know about.