Headphone comparison: open-back versus closed-back
16/8/2022
Translation: Megan Cornish
Closed-back headphones block sound, while open-back ones let it through. But how do they work? Who needs open-back and who needs a closed-back model?
An open society, an open mind, an open post office counter, open positions, recently even open trouser flies: it’s all positive. We tend not to like closed doors, counters and level crossings.
When it comes to headphones, open-back and closed-back models are pretty much equal. Both can sound good or less good. Which is better depends mainly on the intended use and personal preference. With open-back headphones, more music leaks out and, conversely, more noise from your environment reaches your ears. This means that open-back models aren’t ideal for commuting on public transport or working in open-plan offices. Some people, like our CFO, still prefer open-back headphones because they don’t like the closed-off feeling.
As an example, I’m comparing the closed-back Beyerdynamic 770 DT Pro headphones with the open-back DT 990 Pro. Apart from this difference, they’re very similar, making them suitable for a direct comparison.
The terms open and closed are not absolute. Even with the closed-back 770, sound penetrates to the outside, and the open-back 990 doesn’t let everything out unfiltered. Headphones can be more or less open. That’s why there are also semi-open headphones as a middle ground. In the Beyerdynamic range, this is the DT 880 Pro.
As a rule, the difference between open-back and closed-back headphones is whether they’re over-ear, i.e. models that enclose the ear. But on-ear and in-ear headphones can also be designed open or closed. The Sony LinkBuds in-ears, for example, have a hole in them and are therefore open.
Shielding and permeability
The open design is visible: on the back of the Beyerdynamic DT 990 Pro, you can see a grid with fabric behind it. This makes the ear cup sound permeable. The 770, in contrast, has a closed plastic shell.
Closed-back headphones are quieter for other people, disturbing them less. However, there isn’t a huge difference between the two Beyerdynamic models. Even with the closed-back headphones, I can definitely still annoy those around me, but the sound that penetrates to the outside is much more hollow.
The situation is similar with sound that penetrates in the opposite direction, i.e. from the outside to the ear. Other people’s conversations are less loud when wearing the DT 770 Pro. But the same still applies: the shielding isn’t strong enough to be able to concentrate while someone nearby is having a conversation. For this, the headphones would have to have active noise cancelling in addition to a closed-back design.
Outside noise also sounds different with the closed-back model than with the open-back one. High frequencies are blocked well, making conversations less easy to understand. Low frequencies, on the other hand, penetrate. With the 990, it’s the other way around. I find that more pleasant, even if the level is louder overall.
What really surprised me was the shielding of very low rumbles, such as bass beats or footsteps on the upper floor of the house. The open DT 990 Pro filters them so that they’re heard as relatively pleasant noises rather than an unpleasant pressure wave. The 770 does nothing in this area.
Because I found it so strange, I measured it. In this somewhat ridiculous-looking experimental arrangement, the sound is directed from the outside onto the headphones by a second set of headphones placed over the top. The inner headphones are measured with the miniDSP Ears binaural microphone and REW software.
Of course, the results of this tinkering should be taken with a pinch of salt. Broadly speaking, the result matches my listening experience. The curves show that low frequencies are louder from the outside with the 770 (red/green) than with the 990, while high frequencies are quieter.
The sound
In my opinion, the two headphones sound very similar: fairly neutral, but with powerful highs. However, the 770 seems to have a little more punch in the bass range.
The frequency response measured with the miniDSP confirms my impression: the DT 770 Pro (blue line) has louder deflections in the low bass range.
The measurements from rtings.com also show that the DT 770 is louder in the deep bass range, but it’s a fair bit quieter in the lower mids.
Both my own measurements and the ones from rtings.com also show that the closed-back DT 770 Pro shows much larger individual measurement fluctuations in the bass range.
The explanation: closed-back headphones need the seal to get the bass right. The seal depends on how the cup rests on the head. In the bass range, even small differences can have a big impact. This isn’t the case with open-back headphones, so they’re more consistent.
There is another difference, but it’s difficult to describe. The 990 somehow sounds more open, broader. This could be because I also hear a little bit from the right channel in my left ear and vice versa. Another explanation is that the closed-back headphones form a kind of resonating body.
Other differences
I notice the biggest difference between open-back and closed-back when I raise my own voice. With the open-back model, it sounds like it would without the headphones. With a closed-back version, it’s more like my ears are blocked and I can only hear myself from the inside. If you like to sing along while listening to music or want to chat with headphones on, the open-back design is clearly superior.
Air circulates better in open-back headphones. If your ears get hot quickly, you should find the open design more comfortable, especially as closed-back headphones exert more contact pressure on average to achieve an optimal seal.
However, I have no problems with the heat when it comes to the Beyerdynamic headphones, even the closed-back model. Maybe it’s the really comfortable fabric cushion covers. The DT 770 Pro don’t press any harder either.
Verdict
In a quiet environment where I won’t disturb anyone, I prefer the open Beyerdynamic DT 990 Pro to its closed-back counterpart. This model sounds a little nicer and I hear my own voice as naturally as if I wasn’t wearing headphones. Surprisingly, it also does a better job of blocking out ambient noise in the lowest frequencies.
The closed DT 770 Pro reduces the level of outside noise, but it wouldn’t be effective enough for undisturbed work. I prefer closed-back headphones with active noise cancelling. Models with a transparency mode combine the aim of both designs for everyday use.
David Lee
Senior Editor
David.Lee@digitecgalaxus.chMy interest in IT and writing landed me in tech journalism early on (2000). I want to know how we can use technology without being used. Outside of the office, I’m a keen musician who makes up for lacking talent with excessive enthusiasm.
