What is ANC?

Active Noise Cancellation (ANC) is a technology that reduces unwanted background noise arriving at the eardrum of the user. ANC captures background noise through microphones and generates antinoise (an inverse waveform of the background noise) using the chipset. This anti-noise is then projected/played through the headset speaker. This anti-noise and the active noise cancel each other before reaching the ear of the user, as shown in Figure 1-1.

Figure 1-1 ANC conceptual diagram

Due to the properties of sound waves, ANC is most effective in the low-frequency portion of the acoustic spectrum (between 100 Hz and 1 kHz). Depending on the fit (mechanical) and acoustic properties, ANC can cancel noise in higher frequencies.

It is difficult to make ANC cancel out high-frequency noise. However, high-frequency noise is blocked by passive isolation such as an ear-cup headset. 

Passive noise isolation is not effective with low-frequency sound waves (especially sounds below 1 kHz). Passive noise isolation and ANC technology are mutually complementary methods of providing the user with a comfortable listening environment. 

It is important to note that ANC depends a great deal on the effectiveness of an electro-mechanical component such as a speaker or receiver, which is required for generating low-frequency sound waves. Because of these characteristics, ANC system performance depends not only upon the ANC technology itself, but also on the acoustic and electro-acoustic hardware design.