I am looking to buy some noise isolating (not noise cancelling) headphones, but I am very confused right now. Initially I thought that impedance was a good measure of the capacity for a pair of headphones to block outside noise, but after reading a review on Amazon to this product I am not convinced because in the description for these headphones an impedance rating of 50 ohms is given and a reviewer has made the following statement:

These headphones are not at all designed to be sound isolating. They are completely open - any other sound in your listening environment will come in, and anyone else around you will be able to hear what you're listening to.

So I ask the following:

  1. What is a good technical spec to judge the ability of a pair of headphones to block outside noise?

  2. What is a good pair of noise isolating over ear headphones?

  • 1
    Do you need them for something music related? If not, this question may be off topic. Noise isolating headphones are most often used with loud tools like lawn mowers.
    – h22
    Jun 22, 2014 at 12:45
  • 1
    @AudriusMeškauskas They are indeed music related. I have just found a forum relating to the answer I am looking for here: drummerworld.com/forums/archive/index.php/t-36091.html. Many drummers use noise isolating headphones so they can block out the loud drums and better hear the melody they are playing to.
    – Klik
    Jun 22, 2014 at 18:41

3 Answers 3


This is what the impedance spec refers to:


It's nothing to do with sound isolation.

I doubt there is any spec that can accurately represent the level of sound isolation.
This is because the level of isolation is almost entirely dependent on the fit; How well they fit to your particular head shape and the pressure applied.

The headphones you link are open backed so will have very little isolation.


In-ear headphones can achieve reasonable sound isolation as they can form an air tight fit in the ear canal. Over ear (closed back) head phones can't form an air tight fit so can't achieve any where near the level of isolation as in ears. If over ears applied enough pressure to become air tight they'd be so tight it'd be unbearable.

Your need to try on a few different over ears to see which achieve a good fit on your particular head. Be aware that those that provide the best isolation may be tight enough to give you a headache after an hour or two.

  • There is a spec for isolation called the NRR or Noise Reduction Rating, but I'm not aware of that being measured or reported for close-backed headphones intended for music listening. It is used often for earplugs and other noise safety equipment, including equipment that also functions as headphones designed for voice communications (e.g., for constuction work), as opposed to music listening. As to how accurate NRR specs are, well that's another question. They are kind of like A-weighted SPLs in that they try to deal with safety, primarily. Jul 12, 2016 at 14:37

ATTENUATION. This is the technical term for a reduction in signal strength (i.e. a reduction in the volume).

Isolation or cancellation? The other responders seem to miss that many solutions for noise reduction are using active inverse wave cancellation rather than passive isolation--which is what I recommend for maximum hearing protection and listening enjoyment.

Look into Etymotic research headphones, I am a drummer and big fan of their products--even their $60 product is mind-blowingly better than most alternatives and is still compatible with high end custom fit ear protection.

Admittedly these are insert earphones rather than closed-back, over-the-ear headphones, but the attenuation is impressive 35-45 db and relatively flat so things sound better than wearing foam ear plugs with even higher sound attenuation.

EDIT: adding link to head-fi thread:



An effective way to have noise-isolating headphones is to use earphones under industrial muffs. You don't specify whether they are to stop others hearing what you're listening to, or to stop extraneous noise getting to your ears, but this will work either way.Obviously, full size headphones won't do it, but smaller, good quality in-ear phones will. The impedence values will not affect the situation.

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