Noise cancelling devices reduce ambient or background noise through a method called active noise control. According to Wikipedia, active noise control is where another noise is introduced so as to cancel out the first. Noise cancelling headphones that are used by autistic people are way different from passive headphones that use a method of sound proofing to block out any noise getting into your ears. For safety of the autistic child , you do not want them to be completely sound proofed from the noise because this could create accidents such as when the child refuses to move away from honking cars since they cannot hear them or when they do not respond to your calling them since they are completely blocked off from such sounds.
How do they work or how are they designed
Noise cancelling devices use active noise control. This means that to cancel out noise A, a secondary noise B is introduced that cancels out noise A. Noise B has to be desirable to the listener. The devices have a microphone that measures the background noise, generate a waveform that is the exact negative of the background noise and then mix it with some audio signal that is pleasant to the person wearing the earmuffs.
Areas where the devices are used
- As headphones for autism: Adults as well as children with autism spectrum disorder usually find that they over process sounds in the environment. Say for example that they are in class learning but a siren outside the class goes off, the person is not able to detach the noise of the siren. They get too much stimulated and so they stop concentrating on what is happening in class. To help them, you need these noise reducing earmuffs so that they can concentrate in what they are doing while muffling the ambient noise.
- As a sleeping aid. Of late, people with insomnia are going for these devices so that they can sleep peacefully without being disturbed or woken up by the background noises in their homes.
- In aviation. While flying, pilots need to focus on the task of making their planes fly. They do not want to hear the cockpit noise but concentrate on the task ahead as well as maintain conversation with the person directing them.
Disadvantages of the noise cancelling devices
- When buying them, you are bound to cough out more dough than you would were you buying the normal headphones
- For active noise control to happen, you need to power the headphones. Therefore, you will need to have a battery on the devices that powers them up
- Noise cancelling devices could be dangerous especially for kids if they are completely muffling the outside noise.
- Adding batteries also means that the weight of the headphones increases. And so does the cost of maintain the headphone
- The circuitry that makes up the headphone may end up causing a hiss on the audio that you are getting.