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How noise canceling works in headphones

Present in the new releases of headphones from major brands, understand a little more about how noise cancellation technology occurs

Headphones with active noise cancellation technology have arrived on the market as an alternative for people who work and / or travel in very noisy environments (such as airports), who need sound clarity to play their music or podcasts without external distractions. There is a variety of headphones on the market with the technology noise canceling (noise cancellation, in Portuguese), but how does this technology work?

What cancellation rudo

To advance in technology, we must first understand a little how the sound waves work. The sound formed by mechanical waves propagated by the air. The air when activated by something that emits sound, that is vibrating, expands and contracts. The sound wave has a direction and from the point where the sound started, that wave can go upwards (positive phase) or downwards (negative phase).

Noise cancellation technology which had a patent created in 1930 and its first prototype launched in 1986, uses destructive interference, which happens when two waves are combined. That is, while the wave in the positive phase is going up and expanding the air, there is a wave in the negative phase going down and contracting the air. With that, the waves cancel each other out, the air is paralyzed and a silence is almost created, allowing you to listen to music without interference.

Destructive interference: when two waves are combined, silence is created (Reproduction: Afd-techtalk)

How the technology works in your headphones

The headphones with noise canceling cancel out those noises that pass through passive isolation, a technology present in most headphones that are manufactured, following models and materials, such as high density foams, which partially block external sound waves. The in-ear headphones they are an example of passive isolation, but for reasons of adaptation to the ears and auditory channels they end up not serving equally to all users.

However, this technology works more for low frequency and steady sounds. In shorter, high-frequency sound waves (higher pitched sounds) the results are slightly less positive. This is because in headphones with active noise cancellation, microphones are embedded inside the headphones and detect external sounds and convert them into an electronic signal. In this way, a circuit with microphones will capture the sounds that will be canceled and another circuit will calculate the opposite versions of these sounds. This calculation can take microseconds to be executed and therefore the efficiency of the technology is higher in constant and low frequency sounds.

Noise cancellation cancels sounds that go beyond passive isolation (Photo: StockSnap)

Some headphones with active noise cancellation may have a noticeable hiss. This hiss produced by the electronic circuit itself, which with a lack of uniformity in the sensors and copper wire, makes the electrons jump, thus producing this noise present in cell phones and even amplifiers. And that is linked to the quality of the headphones as well. There are options in the market where the cancellation of active sounds is very efficient, such as the WH – 1000XM3, from Sony.

For those looking for smaller headset options with the technology, AirPods Pro, from Apple and the WF-100XM3, from Sony, are recommended for combining technology with the practicality of earbuds (wireless headphones, in Portuguese).

However, in the future we may not even need devices in our ears to enjoy the benefits of active noise cancellation. Cars with accelerometers combined with microphones to mediate the vibration of external sounds are already trying to reduce the noise that passengers hear. Engineers at the University of Illinois are also researching how to unify active noise cancellation technology with those of wireless signals that are transmitted a million times faster than sound.

While the future does not come, if you like to listen to your music without external interruptions, noise canceling headphones are the best option for you. Take advantage of our tips and dive deep into this universe.

Source: Seeker