What is Active Noise Cancellation & how does it work?

Active noise cancellation: clearer sound is here

We use headphones almost every day. Starting from taking calls to listening to music, we use them. When we listen to headphones, we also hear lots of background noise. Exactly in such a situation, Active noise cancellation does the job. It filters out outside noise, and you hear exactly what you want. The invention of noise-canceling headphones helps you listen to what you are listening to.

Besides, active noise cancellation is a method of lowering the unnecessary sound by creating another sound to cancel out the first. It is somewhat difficult to understand at first glance, but rather it’s simple.

Also, the technology actually dates back to the 1930s. The recent evolution in mobiles and music listening give new life to this technology. A few years back, it was available only to expensive headphones, but as technology advances, less expensive headphones come with this technology.

How does active noise cancellation work?

First of all, the sound is nothing but a wave that passes through the air, and once it reaches the ear, we hear the sound. This wave consists of periods of compression and rarefaction. The noise-canceling speaker creates waves with the same amplitude but in an inverted manner. As a result, two waves collide and form a new wave that reaches to destination. The collision in waves cancels each other out. In scientific terms, it is called interference.

Let’s understand this in more simple language. We will take an example of noise-canceling headphones. Active noise cancellation effectively reduces the outside or unwanted sound. In this system, microphones listen to the outside and inside sounds around the headphone.

The chip-set further processes outside sound electronically and inverts sound wave, and sends it back to the speaker inside the headphone. So, this inverted sound wave gets into the output sound wave created by the headphone speaker. By the time it reaches to ear, these waves cancel out each other, and you hear pure music or whatever you are listening to more clearly without any background noise. So, it is like taking +1 from outside and adding -1 to inside to make it 0.

The challenge

As we know, noise cancellation works theoretically, but it isn’t easy to practically do it. It is essential to capture background sound correctly so that engineers could provide max attenuation. If done incorrectly, the sound wave may misalign and won’t give the maximum possible output before it reaches your ear. Hence, you will hear outside sounds. So, the perfect alignment of both sound waves is vital.

Furthermore, the electronic conversion also adds its own sound. Hence, it is vital to fine-tune everything to achieve perfect cancellation of sound waves & also, the sound you hear outside and inside the headphones. Sound capture plays a very vital role in actively canceling the noise.

Active vs passive noise cancellation

The noise cancellation is nothing but reducing outside noise to hear what you are listening to clearly. Active noise cancellation involves electronics and power sources, while passive noise cancellation requires various materials to reduce noise.

Active noise cancellation works best in close or small environments like headphones. On the other hand, passive noise cancellation works best in large areas. Active noise cancellation can handle low-frequency sounds, while passive noise cancellation is suitable for high-frequency sounds. Also, active noise cancellation involves the cancellation of sound waves, while passive noise cancellation involves the isolation of sound waves.

Advantages

The most important advantage is the silence created by active noise cancellation technology. So you can sleep comfortably in crowded spaces. You can lower the volume of music as you can hear it clearly at a low sound level.

This technology is beneficial for people traveling more often via airplanes and trains. You can also easily concentrate on things you are doing, specifically in busier spaces.

Disadvantages

The noise-canceling technology is costly. The electronics involved are very complex, and high-frequency noise may distort the sound and reduce overall sound quality.

Noise-canceling technology requires external power to work effectively. The overall design of headphones with this technology is bulky and heavy. You may hear humming sounds sometimes. This hum maybe not comfortable to some people, limiting the use due to such sounds.

Image Courtesy: Cirrus Logic