Over-ear headphones come in all sorts of shapes and sizes, but they can primarily be broken down into just two types: open-back or closed-back. Whether a pair of over-ears is open or closed isn't always immediately apparent to the eye, but essentially it comes down to their structure and the consequent effect on performance.
Closed-back is unarguably the most common type, with pretty much all wireless over-ear headphones being closed-back, and most wired over-ears also opting for a closed design. Open-back is less common and predominantly found in wired headphones (though open-back headphone king Grado has uniquely applied the design to its GW100x wireless headphones).
While headphones manufacturers produce open- and closed-back headphones to varying degrees of quality, in our experience the fundamental differences between open and closed designs are apparent...
Open-back headphones win on sound and comfort
An open-back pair of headphones doesn’t have an enclosure behind its drivers, which means that sound is fired both towards and away from the listener’s ears. Therefore, if you sit next to anyone using a pair of open-back headphones, the chances are that you’ll have no problem hearing their music, albeit with a thin and tizzy tone. You'd be hearing the sound being fired away from the listener’s ears and out of the headphone's ear cups (which often have holes for that sound to escape through).
It goes the other way too, with outside noises coming through to disturb the listening experience. With this kind of design, there is little sense of isolation from the environment and you can hear pretty much everything going on around you. Want to enjoy open-back headphones on a bus, train or plane? Good luck. These are definitely headphones better enjoyed in the quiet privacy of your own home, where noisy distractions are – we hope – limited.
Why do some manufacturers still persist in making such designs, then? Well, there are some really important advantages when it comes to sound quality. The lack of an enclosure behind the drive unit means that the rearward firing sound is free to escape.
In a closed design, this sonic energy would be trapped and excite resonances in the enclosure, causing unwanted noise. This is sound you don't want and it overlays that made by the drive unit. The result is a loss of clarity, transparency and resolution. Also, there is a good chance that any sound bouncing around inside that closed enclosure could work its way back out through the drive unit diaphragm and add to its output – again, detrimental to sound quality.
It doesn't end there, either. The inherent springiness in the trapped air behind the driver could restrict the movement of the diaphragm during larger excursions, which would affect the way the headphones render the music’s dynamics and limit performance at higher volume levels.
When it comes to pure sound quality, open-back designs hold most of the aces... but not all. All things being equal, closed-backs usually have the punchier, more muscular bass. They tend to sound more solid and substantial as a result, and possibly even more exciting. Sure, as a breed they do come out second-best in terms of outright transparency, detail resolution and dynamic expression, but as the Beyerdynamic DT 700 Pro X and Sennheiser HD820 prove, it is still possible to get a great performance if you throw enough engineering know-how at the issues.
Comfort can also be helped by an open design. Ears heat up less over extended listening sessions, while the lack of an enclosure offers the potential for reduced weight. Great examples of open designs include the Focal Clear Mg and Grado SR325x, both of which feature on our best over-ear headphones list.
Closed-back headphones are more practical
Move away from sound quality to more practical considerations, and closed-back designs pile on the plus points. Such headphones are better able to isolate the listener from outside distractions and make it possible to sit in the same room as someone without disturbing them.
If you’re out and about, closed-back is the only way to go, and adding wireless and noise-cancelling technologies simply enhances their advantage in this context. Wireless functionality and open-back designs simply do not go hand in hand.
Factor the typically greater sonic muscularity into the equation and it is no wonder that such designs become the obvious choice for most people in this increasingly portable world.
Closed-back vs open-back: which should you choose?
The answer isn’t straightforward or indeed the same for everyone. If you’re after the last word in sound quality and want a pair of over-ear headphones to use at home with your desktop or hi-fi system, the open route is the one to take. You'll get a generally more insightful, clearer sound.
But if real life intrudes and your needs take in domestic harmony or on-the-go, less-than-silent listening environments, then you only really have one option – the practicality of a closed-back design will win every time.
Whichever design you settle on, both feature heavily in our best over-ear headphones list, so make sure to check out our expert picks – all tried and tested by our dedicated reviews team – before you buy.
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