What is passive noise cancellation

What Is Passive Noise Cancellation?

To discuss passive noise cancellation is difficult without first defining the meaning of noise cancellation and its various forms. Noise cancellation is defined as a number of technological means by which an audio device approaches the elimination of unwanted noise. The form of noise cancellation varies from device to device. Including passive noise cancellation, there is also adaptive noise cancellation, ambient noise cancellation, and of course the inverse active noise cancellation. 

With the rise of personal tech devices such as smartphones, tablets, and smart speakers, good headphones are practically a given.  With the recent growth of remote work and video conferencing, noise cancellation of any type is a useful feature to have to avoid any possible directions while on the job. Below will be brief definitions and summaries of the two main types of noise cancellation, active and passive, alongside their benefits.

Active Noise Cancellation 

Active noise cancellation headphones 1
Source: PxHere

Headphones of the active noise cancellation type make use of built-in technology that allows them to find and destroy sounds before they reach your ears. They accomplish this feat by the headphones having small microphones in each ear cup.  Each microphone listens for any noise coming from outside the headphones and then generating the polar opposite frequency, called antiphase.  When the antiphase frequency collides with the corresponding audio, the two sounds will then completely cancel both sounds out.  This then leaves only the audio coming through the headphones for the listener. The largest downside of active noise cancellation is that the headphones usually require some form of extra power in the form of internal batteries to make use of the function.

Passive Noise Cancellation

Passive Noise Cancellation headphones, in contrast, is the noise that gets blocked from the ear solely based on the design of the ear pieces. This goes for the physical design of the headphones rather than the technical.  The shape, size, and material are all contributing factors for passive noise cancellation, which is also referred more accurately as noise isolating. This method is applied to both in-ear buds and over-ear headphones. Strong passive noise cancellation can nullify the need for power or battery consumption found in active noise cancellation headphones. Due to the lack of the extra functionality, strictly passive noise cancellation headphones also tend to be more affordable then their active powered counterparts.

Total Cancellation

Total cancellation is the sum total cancellation experienced from both the active and passive noise cancellation when the headphones incorporate both. There is usually some form of passive noise cancellation with every model of headphone or earbud so when used in tandem with any active noise cancellation functionality, the resulting audio that is blocked should be pronounced. 

The Audio Difference

Active noise cancellation headphones
Source: Apple

With active noise cancellation relying on antiphases to block unwanted sound, this can create a separate noise that can sometimes be heard and picked up inside the headphones themselves. Some users report some form of humming sound being heard. This tends to lead to a perceived period of lowered sound quality. When looking at a large portion of the high end headphones, usually reserved for DJs and musicians, many do not have active noise cancellation as an option as a result.  If they do, it is usually only an optional switch that can be turned on or off at the convenience of the user. 

The Price

Most noise-canceling headphones grant the option to turn active noise cancellation on or off. If you do not intend to use active noise cancellation, however, this can end up being a wasteful and expensive option. The better choice at that point would be to look into a headset like the Jabra Elite 45H. This can prevent any unwanted price increase while still preserving the audio quality you are needing. 

The Feeling of Pressure

Another thing to keep in mind is that headphones that resort to active noise cancellation tend to create a certain sensation of pressure in certain individuals. Accounts range from feeling like the cabin pressure of a plane changing or driving through some form of subterranean tunnel.  While not painful, it has been noted that some individuals may find the sensation uncomfortable over long periods. Bear this information in mind when deciding on the model of headphones.

Conclusion

When looking at passive noise cancellation, it is important to understand the functions of both passive and active. Knowing the downsides in the form of audio quality and comfort assists any buyer in their goal to find the headset that meets their particular needs.

By Ciaran Carbery-Shaha

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