HowLoudHow Many Decibels Do Noise-Cancelling Headphones Block?
Good noise-cancelling headphones take roughly 20–30 dB off steady, low-pitched noise such as engines, fans and air conditioning, and 10–20 dB off voices, clatter and other sharp or high-pitched sounds. They make a plane cabin feel like a quiet office, but they are not rated hearing protection: for power tools or concerts use earplugs or ear muffs.
Two kinds of noise reduction
Every pair of over-ear or in-ear headphones blocks some sound just by sealing the ear. That passive isolation works best on high frequencies: a good seal removes 15–25 dB of chatter, keyboard clicks and hiss, and very little of a deep engine drone. Active noise cancelling (ANC) adds microphones that listen to the outside noise and play an inverted copy of it, so the two waves cancel at the eardrum. ANC is strongest at low frequencies, roughly 50–1,000 Hz, exactly where passive isolation is weakest. The two together are what makes modern ANC headphones so effective.
| Noise | Mostly | Typical reduction |
|---|---|---|
| Aircraft cabin, train, bus engine | Low, steady | 25–30 dB |
| Office air conditioning, fans | Low, steady | 20–30 dB |
| Traffic outside a window | Low + mid | 15–25 dB |
| Voices in an open-plan office or café | Mid, changing | 10–20 dB |
| Crying baby, alarms, clattering dishes | High, sudden | 10–15 dB |
| Gunshots, hammering, fireworks | Impulse | Passive seal only; ANC is too slow |
Figures are typical for current premium over-ear and in-ear models with a good fit. A loose fit, glasses frames or the wrong ear-tip size can halve the passive part.
What is left at common noise levels
| Around you | Example | With ANC on |
|---|---|---|
| 60 dB | Open-plan office, conversation | about 40–45 dB: a quiet library |
| 75 dB | Busy road, train interior | about 50–55 dB: moderate rain |
| 80 dB | Aircraft cabin at cruise | about 50–60 dB: a calm room |
| 95 dB | Subway platform, loud bar | about 70–80 dB: still loud for voices and sudden sounds |
| 110 dB | Concert near the stage | about 85–95 dB: still above the damage threshold |
Do noise-cancelling headphones protect your hearing?
Indirectly, yes; directly, no. The real benefit is that you no longer need to turn your music up to hear it over the background. People tend to raise the volume until music sits comfortably above the noise around them, so on a 80 dB train that easily means 90 dB in the ears. With ANC taking 25 dB off the train, the same music is clear at 65–70 dB, comfortably inside the safe zone.
What ANC headphones are not is protective equipment. They carry no Noise Reduction Rating (NRR), their cancelling is weak against sudden and high-pitched sounds, and they can lift slightly off the ear when you move. In a workshop, at a concert or on a shooting range, use rated hearing protection:
- Foam earplugs, labelled NRR 29–33, give roughly 15–25 dB of real-world protection when inserted properly.
- Musicians' earplugs take a flat 15–20 dB off so music still sounds natural.
- Ear muffs, NRR 20–30, are quick to put on and off for power tools.
- Plugs plus muffs together for the loudest jobs, above about 105 dB.
Can ANC itself damage hearing?
No. The cancelling signal is an inverted copy of the noise, so it lowers the total level at the eardrum rather than adding to it. Some people feel a sense of pressure or slight dizziness with strong ANC, especially at first; it is harmless and usually fades, and most headphones let you choose a lighter setting. The hiss some models produce in a silent room is the ANC circuit's own noise floor, typically below 30 dB.
Check it with a meter
You cannot measure what reaches your eardrum with a phone, but you can measure the room. Open the online decibel meter, note the level of your commute, office or flight, and subtract 20–30 dB for low drones or 10–20 dB for voices: that is roughly what you hear with ANC on.
Frequently asked questions
How many dB do noise-cancelling headphones reduce?
About 20–30 dB for steady low-frequency noise and 10–20 dB for voices and higher sounds, combining active cancelling with the passive seal of the ear cups or tips.
Are noise-cancelling headphones good enough for a concert?
No. A concert at 100–110 dB stays above the 85 dB damage threshold even with ANC, and music is full of the mid and high frequencies ANC handles worst. Use musicians' earplugs.
Can I wear noise-cancelling headphones with a lawn mower or power tools?
Not as your only protection. Use rated ear muffs or earplugs; some muffs have built-in Bluetooth if you want music.
Do in-ear or over-ear headphones block more?
Both can reach similar figures. In-ears depend heavily on ear-tip fit; over-ears depend on the seal around glasses and hair. The best one is the one that seals well on you.