True wireless earbuds (TWS) have become very popular lately. There is another feature that is popular with TWSs: Active noise cancellation (ANC). This feature, which was previously found in high-end headphones, has now even come to affordable headphones. How does this feature, which increases the pleasure of listening to music by blocking outside sounds in crowded and noisy places, work?What is active noise canceling?
Active noise canceling technology is a technology that reduces the noise reaching the ear by producing opposing sound waves against the sound waves coming from outside. It does this with the principle of “destructive interference”, which neutralizes each other when two waves with the same frequency and amplitude meet.
To understand how the system works, let’s imagine a pond with ripples on its surface. If you throw a pebble into a pond, it creates a circular wave that propagates outward. If a pebble is thrown at the same place and at the same time, a wave similar to the first one, but larger, is formed. This resulting wave is the sum of the two waves. This is called “constructive interference”.
If you throw a stone at the same place in the same pond, this time with a slight delay, the second wave will be slightly behind the first and the peaks and valleys of the two waves will not be synchronized. So the two waves will be subtracted from each other and a smaller wave or no wave will be formed. This is called “destructive interference”.
How does active noise cancellation work?
Active noise canceling uses destructive interference to reduce the impact of noise. The noise is listened to through the microphone, processed and analyzed by a processor, and a counter-noise signal is produced and transmitted to the ear through the speaker. This counter-noise signal is a signal with the same frequency and magnitude as the incoming noise but in opposite phase. When two waves meet, they cancel each other’s effect. In this way, the noise does not reach the ear or reaches very little. The process works continuously and in real time, analyzing changing sounds and trying to block out the noise.
The system generally performs well in blocking low-frequency and constant noises such as engine noise, airplane and train noise. It produces less successful results with high-frequency and intermittent sounds such as human voice, horn sound or dog barking. Of course, the quality of the microphone, processor and speaker used also affects performance. Apart from active noise cancellation, noise cancellation performance through passive insulation also plays an important role.
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