Noise isolation is the headphones' ability to block ambient noise passively and/or actively.
Passive Isolation is a physical contribution to isolation and depends on headphone or earbud design. Typically, more padding on the ear cups or earbuds results in better passive isolation.
Active cancellation refers to the noise cancelling technology that enhances isolation by nullifying sounds that seep into the headphones. Well-isolated headphones provide a noise-free listening experience even in loud environments or on busy commutes.
For noise cancelling performance, we test the overall attenuation, bass, mid and treble attenuation and self-noise.
When it matters
If you’re often in noisy environments, a well-isolated pair of headphones, will keep the ambient noise from distracting you from your listening experience.
Although listening at high volumes naturally overpowers ambient noise of lesser amplitudes, more active and passive isolation is required at lower volumes, or if the headphones are simply used to block sound to make it easier to focus.
Poor noise isolation can be a significant issue, depending on the loudness of your environment. Urban commutes and international travel are examples of when you might require good noise isolation.