However, despite noise cancelling headphones being very popular, there is still a lot of confusion when it comes to the technology itself. Manufacturers often take a rather liberal stance with their terminology and confuse noise cancelling technology with a much simpler noise isolation. On top of this, you need to understand the most fundamental principles behind noise-cancelling technology to be able to distinguish empty marketing claims from really useful features and innovations.
Before we compare noise isolation and noise-cancelling technology, let us first take a look at how each of them works.
How do noise-isolating headphones work?
Noise isolating headphones are extremely simple in terms of how they achieve the desired outside sound reduction. The body of the earphone itself is used to block out sounds exactly like you do when you insert a pair of ear plugs for sleeping into your ears.
The construction plays the most important part since closed-back headphones and earphones provide the best isolation and thus block out the most sound. It is said, that typical closed-back headphones can block anywhere from 8 to 12 dB, and earphones can block from 10 to 15 dB. Open and semi-open headphones and earphones do provide some degree of isolation but it usually is not enough to block even semi-loud conversation which makes them difficult to use in louder environments. The advantage of semi-open and open headphone design is better performance and sound quality. While closed headphones can sound just as good, or even better, than open headphones, sound engineers have to work much harder to achieve this result.
We advise you to always check online reviews and user recommendations before purchasing a pair of noise isolating headphones.
How do noise-cancelling headphones work?
Noise cancelling headphones employ active noise control mechanism to reduce unwanted outside noise and help you enjoy your music and hear more of what is being said – something that is really important in aviation or industrial setting.
The history of noise cancelling technology goes back much further than you might have expected. The first patent and description of the technology itself goes back to 1930s with first systems being created to cancel the noise in helicopter and airplane cockpits during 1950s. From there, noise cancelling technology steadily improved and was successfully applied in many different areas.
So how does this technology work? All sound is really just compression and rarefaction of the air around us. The engines of, for example, the aircraft produce a sound wave of constant amplitude and constant wavelength. If you produce another sound with the same amplitude-wavelength but opposite phase you get an antiphase. Phase and antiphase cancel each other out, in a process called interference, and the result is a complete silence.
Noise cancelling headphones have a small microphone that is used to capture the ambient sound that surrounds us and sophisticated internal electronics analyze this information and produce a noise cancelling antiphase. The volume of the noise is thus reduced and we can concentrate on our music without being disturbed.
This type of active noise cancelling works best with lower frequencies like airplane or engine noise and to a greater extend even street or office noise.
Which technology should I choose?
Both noise isolation and active noise cancelling technology have their pros and cons. You should carefully consider all of them as they relate to your personal preference and application before making your final decision.
Pros and cons of passive noise isolation
Passive noise isolation is much cheaper to make than active noise cancelling. You do not need any additional microphones or audio processors since it essentially just physically prevents sound waves from ever hitting your eardrum. Some headphones and earphones offer an outstanding level of passive sound protection that might not be enough to block a loud airplane engine, but it will definitely be more than sufficient for your typical office environment or noisy dorm room.
The second most important advantage of noise isolating headphones is that they do not require any additional power source. Active noise cancelling headphones often rely on batteries to function and this can become problematic if you are in a situation where it is not easy to stock up on batteries.
All cons of passive noise isolation concern its effectiveness. Active systems are able to block out louder sounds and are thus preferred in those applications where a high signal-to-noise ratio is essential.
Pros and cons of active noise cancelling
Active noise cancelling systems are always improving and the quality of noise cancelling that you can get today is simply astonishing. These systems have been in use for decades in professional setting offer a reliable and effective solution for those who seek maximum comfort. If you are often travelling by plane or train and need to focus on your work or enjoy a good sleep, then noise cancelling headphones are the way to go.
However, this technology is not without its drawbacks and you need to be aware of them so that you do not run into any surprises. Noise cancelling headphones are typically more expensive than equivalent noise isolating counterparts. You are paying not only for the headphones themselves but also for a highly accurate microphones and advance digital processing units that constantly analyse all captured sound from the outside.
Some lower quality noise cancelling headphones also somewhat degrade the overall sound quality and may even introduce a noticeable hiss when the noise cancelling is in its active state.
But the most important drawback to noise cancelling headphones is that they really on a steady supply of power beyond what a regular audio jack is able to provide. Some noise cancelling headphones have a built-in battery while others require AA or AAA batteries to operate. This can become especially troublesome if particular noise cancelling headphones are not able to continue playing without battery power.