Active Noise-cancelling headphones primarily work by:

Active noise-cancelling (ANC) headphones are designed to reduce or eliminate external noise, allowing the listener to enjoy their audio content without distractions. These headphones achieve this by generating sound waves that counteract the incoming noise, resulting in a quieter listening experience.

How do active noise-cancelling headphones work?

Active noise-cancelling headphones work through a combination of technology and algorithms. The process involves several steps:

1. Microphones: ANC headphones feature built-in microphones that are strategically placed to capture the external sound waves. These microphones act as receivers, detecting and analyzing the incoming noise.

2. Analysis: Once the microphones capture the external sound, the headphones' internal circuitry processes the audio signal. The circuitry analyzes the sound and identifies the frequencies and amplitudes of the unwanted noise.

3. Creation of mirror sound wave: After analyzing the external noise, the headphones generate a mirror sound wave with the same frequency and amplitude as the unwanted noise. This mirror sound wave is an inverse waveform that cancels out the incoming noise.

4. Combining the mirror sound wave: The mirror sound wave is combined with the original audio signal that the listener wants to hear. By adding the inverse waveform to the incoming noise, the unwanted sound is effectively canceled out.

5. Delivering the audio: The final audio, which now includes the original content and the mirror sound wave, is played through the headphone speakers. The listener perceives a reduction in external noise, allowing for a more immersive audio experience.

Why is option A the correct answer?

Option A, "Sending a mirror sound wave inside the headphone speakers," is the correct answer because active noise-cancelling headphones primarily work by generating a mirror sound wave that cancels out the incoming noise. This mirror sound wave is created based on the analysis of the external sound captured by the built-in microphones. By combining the mirror sound wave with the desired audio signal, the unwanted noise is effectively neutralized.

Option B, "Radiating sound waves externally (to the headphone) to block any incoming sound," is incorrect. Active noise-cancelling headphones do not radiate sound waves externally to block incoming noise. Instead, they generate mirror sound waves internally to cancel out the unwanted noise.

Option C, "Passively blocking all the noise coming inside the microphone," is incorrect. Active noise-cancelling headphones do not rely on passive blocking of noise. Instead, they actively generate counteracting sound waves to neutralize the incoming noise.

Therefore, the correct answer is option A, as it accurately describes the key mechanism behind the functioning of active noise-cancelling headphones.