You need an active noise cancelling (ANC) headphone if you want to block the ambient low-frequency noise, like engine noise in the aeroplane. For example, Sony WH-1000XM (XM1-XM4) series, Bose Quietcomfort series (e.g., 15, 25, 35, earbuds), Apple AirPods Pro, and Samsung Galaxy Buds Live all have ANC.
Active noise cancelling (ANC) is different from noise blocking/isolating, which passively blocks both high and low-frequency noises.
This headphone guide explains what the active noise cancelling (ANC) is and how the active noise cancelling headphone works. It will not only help you understand ANC but also help you choose proper active noise-cancelling headphones.
What is active noise cancelling (ANC)?
Active noise cancelling (ANC, aka active noise control) is a set of audio technologies that actively cancel the ambient noise.
Both the annoying noise and music reach your ear as sound waves transmitted through the air.
So, one simple way to reduce noise is to physically and passively block it. For example, there are many soundproofing materials and technologies.
In the airport, you may notice ground staff are wearing earmuffs to block the engine and other noises. In the shooting clubs, it is also common that earmuffs are used.
Active noise cancelling (ANC), on the contrary, uses negative sound waves to actively cancel the noise.
This means ANC requires at least three components:
- Power source. Active noise cancelling (ANC) always requires a power source to detect and analysis noise and then generate a negative wave.
- Noise detection. Normally, one or more microphones are used to sample the ambient sound.
- Anti-noise sound wave generator. Once the ambient noise is sampled, an active noise cancelling (ANC) system must generate an inverted (negative) sound wave (with similar amplitude) to cancel the low-frequency noise.
When the ambient noise is cancelled, you will get a quieter environment for your music.
Active noise cancelling (ANC) is still evolving, especially on how to sample ambient sound, how to analyze the sampled ambient sound, and eventually how to effectively cancel the low-frequency ambient noise in real-time.
Please note, active noise cancelling (ANC) currently is most effective for low-frequency noise only.
Active noise cancelling (ANC) vs passive noise blocking
As discussed earlier, noise can be “blocked” (passive) and/or “cancelled” (active).