When a brand says its new earbuds have "twice the noise cancellation" or block "up to" a certain decibel figure, that number was measured on that brand's own equipment, under conditions that brand chose, and it is not directly comparable to a rival's claimed number. There is no shared industry test standard that every headphone and earbud maker follows the same way, the way there is for something like an IP rating. A claim can be genuinely true and still tell you almost nothing about how a product will perform against the specific noise in your life, because active noise cancellation works far better against steady, low-frequency drone than against a voice or a sudden clatter.
What an ANC decibel claim is actually measuring
Active noise cancellation works by using microphones to sample the sound around you, generating an inverted version of that sound wave, and playing it back so the two waves cancel each other out. That process is genuinely effective, but it is also frequency-dependent by nature: it works best on continuous, low-frequency, predictable noise, like an airplane engine's drone or a running air conditioner, and it works far worse on noise that is sudden, high-pitched, or irregular, like a dog bark, a car horn, or a person talking near you.
So when a manufacturer publishes a headline reduction figure, that figure is almost always measured under favorable conditions for ANC: a steady, low-frequency test tone, in a controlled acoustic chamber, at a specific frequency the manufacturer selects. It is a real result under those conditions. It is not a promise about how much quieter your commute, your open office, or a crying child on a flight will actually sound.
Why there is no shared standard to compare against
Something like an IP rating follows an internationally defined test that every manufacturer runs the same way, which is why two products with the same IP rating are genuinely comparable, a point covered in more depth in What the Numbers on a Headphone Box Actually Tell You. Noise cancellation has no equivalent that every consumer audio brand is required to follow. Each company can choose its own test frequency, its own reference noise level, its own measurement point, and its own way of describing the result, such as "up to," "average," or "peak" reduction. Two different brands publishing what looks like a similar number may not have measured anything close to the same thing.
This is also why a claim like "twice the noise cancellation" of a previous model needs to be read carefully. Twice a lab measurement is still a lab measurement. It says something real about that brand's own generation-over-generation improvement, under its own test method, and it is not a portable multiplier you can apply to how quiet the product will feel to you in a real environment.
Reading a specific comparison honestly
This is exactly the trap in generation comparisons. Sony WF-1000XM6 vs WF-1000XM5: The Generation Gap on Paper covers a manufacturer claiming a meaningful noise-reduction improvement over its own prior model, and the over-ear equivalent, Sony WH-1000XM6 vs WH-1000XM5: Over-Ear Generations Compared, reads the same kind of claim for a different product line. That kind of same-brand, generation-over-generation claim is more trustworthy than a cross-brand comparison, because at least the test method is likely to be consistent between the two products from the same company. It still does not tell you what either pair will sound like blocking the specific noise in your specific commute.
What actually changes real-world performance, beyond the headline number
A few things matter more than the printed figure once you are past the marketing page:
Fit and seal. For in-ear designs, ANC only works well on top of a good physical seal. A driver and processor that cannot maintain contact with your ear canal loses effectiveness regardless of the chip inside it, which is one reason fit format is the first thing worth deciding, covered in How to Choose Wireless Earbuds Without Trusting Anyone's Score.
The type of noise you actually deal with. ANC is genuinely strong against engine drone, HVAC hum, and other steady low-frequency sound. It is weaker against voices, which is deliberate: most ANC systems are tuned to let some speech-range sound through so you can still hear announcements and conversations, not a flaw in the marketing.
Microphone count and processing, not just the headline claim. Manufacturers increasingly publish supporting detail, like microphone counts or a named processing chip, alongside the reduction figure. That detail does not resolve the cross-brand comparability problem, but a brand that publishes its methodology and hardware specifics alongside the number is giving you more to evaluate than a bare percentage.
How to actually compare ANC across two products
Since a headline number is not reliably comparable across brands, the more useful comparison points are: whether the claim is measured against the brand's own prior generation (more trustworthy) or against unnamed competitors (treat with more skepticism); whether the brand states any detail about test conditions at all; and, for the part that genuinely requires hearing something, an independent outlet running a consistent, repeatable test rig across multiple brands, such as RTINGS or SoundGuys, which at least holds the test method constant across the products it reviews.
Quick reference
| What you see | What it actually tells you |
|---|---|
| "Up to X dB reduction" | A peak result under that brand's own chosen test conditions, usually a steady low-frequency tone |
| "Twice the noise cancellation" (vs. own prior model) | A same-brand, same-method improvement claim; more trustworthy than a cross-brand comparison |
| No stated test method | Treat the figure as marketing framing, not a verifiable spec |
| Independent lab comparison (RTINGS, SoundGuys) | The closest thing to a comparable, cross-brand result, since the test rig stays constant |
FAQ
Can I compare two brands' dB noise-cancellation claims directly?
Not reliably. There is no shared industry test standard, so each brand's figure reflects its own chosen conditions. Treat a cross-brand comparison of headline numbers as marketing framing rather than an apples-to-apples spec.
Does ANC work equally well on all types of noise?
No. It is strongest against continuous, low-frequency, predictable sound, like engine drone or HVAC hum, and weaker against sudden or high-pitched sound and against voices, which most systems intentionally let through so you can still hear people and announcements.
Is a same-brand generation comparison more trustworthy than a cross-brand one?
Generally yes, since a brand is more likely to have used a consistent test method against its own prior product than against a competitor's, though the claim still describes lab conditions, not your specific environment.
Where can I find an ANC comparison that actually holds the test method constant?
An independent outlet that runs the same measurement rig across every product it reviews, such as RTINGS or SoundGuys, gets you closer to a genuinely comparable result than any single brand's marketing page.
Why does my ANC still let some sound through even with a high published reduction figure?
That is partly deliberate design, since most systems reduce speech-range sound less than steady low-frequency noise, and partly a fit issue, since ANC performance for in-ear designs depends on maintaining a good physical seal.