Active vs. Passive Noise Cancellation

Many companies are advertising "active noise cancellation" while others simply speak of "passive isolation", what's the difference?

Passive noise cancellation aka. isolation

This type of noise isolation is the most common and simply the natural way of blocking noise from the outside when wearing headphones. Any closed back headphone or IEM is blocking outside noise by simply being placed over or inside your ears, therefore preventing noise to reach your ear. The effectiveness of the noise reduction one can achieve with passive isolation on full size headphones depends on the materials used for the ear cups, the seal of the ear pads and the clamping pressure of the headphone. For In Ear headphones the most critical aspects are insertion depths and the seal of the tip inside the ear canal.

Closed back cup of the highly isolating HD380 Pro

Active noise cancellation

Many manufacturers are advertising this technology as being a superior method of shielding the listener against outside noise interference. The major difference to passive isolation is that active noise cancelling (ANC) headphones make use of additional hardware and software to detect outside noise and eliminate it. This process of recording the surrounding and counteracting the unwanted noise with inverse sound is what differentiates active from passive noise cancelling.

Naturally, the addition of external microphones, sound processors and the audio processing that is required to make this work is not cheap and requires additional power. That's why all ANC headphones come with internal rechargeable batteries or a compartment for AAA batteries.

External mics on a QC35

Active vs. Passive - What is better?

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