How Does Active Noise Cancelling Work?

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How Does Active Noise Cancelling Work?

Peter Lucier, HIS
Latest posts by Peter Lucier, HIS (see all)

Noise cancelling technology has become a common feature in various industries including headphones and hearing aids. Its radically enhanced listening experiences as we navigate daily life and the range of noise we are exposed to. Noise cancellation features protect hearing health by preventing people from increasing the volume on personal electronic devices (smartphone, speaker, laptop etc.). This is particularly useful for people who regularly commute, have noise sensitivities or some degree of hearing loss, work in noisy environments, regularly listen to music and/or podcasts etc. Though this technology is widely accessible today, you may be wondering how exactly it works so let’s explore the mechanics!

Noise Cancellation Technology

Noise cancellation is the reduction of background noise. There are several ways to “cancel” noise and the product that is best for you will depend on your preferences. This technology can be categorized by:

 

  • Passive:use the material of headphones to provide a protective barrier that reduces the amount of soundwaves you absorb. The most common type is over the ear and in the ear headphones. Over the ear headphones usually have thick foam padding and in the ear headphones also have foam protection. These types of headphones can reduce sound by 15 to 20 decibels. As they are the bulkier option, the size may be a drawback from some who prefer something more compact and don’t necessarily have the space to carry them.

 

  • Active: in addition to doing what passive headphones can do, active noise cancellation (ANC) headphones use technology to actively cancel sound waves. These headphones utilize microphones and speakers to reduce background noise. There are different ways this is implemented.

 

 

Active noise cancellation technology does more to reduce background noise and is commonly the preferred type.

Active Noise Cancellation Types 

The main components of ANC headphones are a microphone, chipset, speaker, and batteries. The microphone collects and records sound waves which are then inverted by the chipset. This means that one wave is delayed to match up with another sound wave, this way they cancel out when added together (rather than being amplified). Inverting the soundwave creates anti-noise which reduces background noise before reaching your inner ear; the speaker then adds this to the output of your device.

 

There are three ways that ANC works:

 

  • Feedforward – is the simple version with the microphone placed on the outside of the headphones which can be useful for earbuds because they have limited surface area. Using a digital signal processor, noise signals are mapped onto the frequency that the user of the headphones will actually hear. However, mapping accurately to ensure noise cancellation can be tricky because it does not account for the specific hearing capabilities of the user. Also, the fit of the headphones on the user can contribute to unwanted background noise seeping through. 

 

  • Feedback – is the opposite of feedforward with the microphone placed inside the ear cup or actual ear (with earbuds). This allows the noise that is recorded by the microphone to more adequality match what the user will hear. Feedback ANC also tends to be more resistant to the impact of wind. 
  • Hybrid – this type is a combination of feedforward and feedback ANC. Hybrid headphones have two high quality microphones which maximizes recording and inverting sound so that background noise is effectively reduced with minimal feedback or other issues. This technology is the more expensive option.

 

 

These types of ANC can block up to 70% of background noise which is ideal for people who regularly navigate environments with increased levels of sound.

Protecting Hearing Health

Knowing about these three types of ANC can help you make a better-informed decision about which headphones would work best for you. This is important because noise cancellation technology reduces the amount of sound you absorb overall which is helpful for protecting your hearing health! Sound is measured in units referred to as decibels and noise over 85 decibels is potentially harmful to hearing. We can easily absorb these levels of noise: listening to music, driving through traffic, using household appliances etc. ANC technology has the capacity to reduce noise by 20 – 40 decibels which is absolutely beneficial to your overall hearing and wellness!

If you have questions about hearing loss prevention or are interested in setting up a hearing test, contact us today!

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