Difference Between Noise Cancelling and Sound Isolating Headphones

There are a ton of different options when looking for the right set of headphones. With so many different choices, many individuals can become easily confused regarding the meaning of some of the technical audio terms. Two terms you may hear regarding headphones are “noise cancelling” and “sound isolating.” These two terms may sound like they are describing the same thing, and while in fact they are very similar, there are subtle differences that become very important as the listener becomes more sophisticated with technology, and especially with the subtleties of audio.

1. Process (passive versus active)

The most obvious difference between noise cancelling and sound isolating, also called noise isolating, headphones, is going to be in the process that they both use to achieve their goal. And while both aim to reduce ambient environmental noise for the listener so that they may better hear the content coming through the headphones, their technique is different. With noise cancelling technology, this is an active process, whereas with noise isolating, it is a passive process.

With noise cancellation, the headphone itself measures the ambient sound and then generates a waveform that is the exact negative of that sound and mixes it with the audio signal that the user is listening through the headphones. Through an analog process, the negative wave negates, or cancels, the ambient noise that is measured.[i] Noise isolation, on the other hand, is a passive process, that simply uses soundproofing to block out the ambient noise, rather than doing anything to counteract it. This is usually achieved by using the body of the earphone to cover the top or the inside of the ear.[ii]

2. Components

Since the active process of noise cancelling is a much more technologically complex process than noise isolation, it is no surprise that there are more components necessary to make it work. And usually this additional equipment tends to cost more, and result in a product that is larger and heavier than noise isolating headphones. In order to actually measure the ambient noise, these headphones must be equipped with a microphone, amplifier, and speaker to pick up, amplify, and play the negative waveform back through the headphone.[iii] Noise isolation technology depends upon its ability to soundproof, or essentially, block out the ambient noises. This is accomplished when the headphone doubles as an earplug. Because of this, there are no additional components necessary in order to make these headphones work and their ability to function well largely depends upon how well they fit the user’s ear.

3. Development and History

Noise cancelling technology was initially explored in the 1950s as a way to minimize or cancel, the noise found in helicopter and airplane cockpits. The technology has advanced and become better through the years and now noise cancelling headsets can be found almost anywhere. Since it is incredibly effective on airplanes, many airlines still provide noise cancelling headphones in some of their premium cabins. Unfortunately, the noise cancelling electronic process may actually reduce the audio quality and even add a high-frequency hiss to the audio stream. Despite this, the noise-cancellation headphones may still be perceived as providing a higher audio quality due to their ability to reduce the ambient noise.[iv]

Since noise isolation is a much less sophisticated technology it has been used for a longer timeframe. And indeed, even the very first headphones developed provided some level of noise isolation simply by covering the outer ear. Some of the more sophisticated models were designed for drummers to monitor recorded sound while minimizing the sound they heard coming directly from the drums. However, the ability to successfully provide true sound isolation is often dependent on how well the buds fit the ear when using ear buds. Other types of headphones, such as closed-back headphones are also particularly suited to physically block the sound.[v] Typically both noise cancellation headphones and noise isolating headphones can provide a reduction of anywhere from 8 to 25 decibels of ambient noise.[vi]

4. Environments well-suited to each

Due to the fact that noise cancellation came about as a way to minimize ambient noise during travel, it is no surprise that these headsets function best in environments with constant, low-frequency noise. They are much less effective when used with other types of noise or when the noises constantly change.[vii] The mid-range frequencies are much less affected by noise cancellation and the higher range frequency even less so. For this reason, most sound cancelling headphones also rely on noise isolation in order to minimize the other sounds.[viii] True sound isolating headphones block all sound frequencies.

5. Power source

Due to the extra electronic components required by the noise cancelling headphones, they also require some sort of power source, typically a battery that either needs to be replaced or recharged regularly. Sometimes the power may also be delivered using a USB port. Unfortunately, some noise cancelling headphones will not function at all, not even as regular headphones, when there is no power.[ix] With noise isolating headphones, there is no power needed. The noise reduction relies on soundproofing that comes from foam molded to fit the outer ear canal. This means that they can be used anywhere and at any time without a need for batteries or any other power source.

6. Price

Again, with the noise cancelling headphones need for additional electronic components, they are frequently substantially costlier than the noise isolating headphones. Quality sound isolating headphones can be purchased starting at $99, but comparable noise cancelling headphones would likely be several hundred dollars.[x]

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