Headphones: A beginner's guide to terminology and technology

Headphones are a category of electronics with two very different types of users. On one hand, you've got the buyer that settles for "decent" sound for their podcasts, music, videos, and phone calls. On the other, you've got enthusiasts and audiophiles that demand the best sound, carefully selecting headphones that optimize every aspect of the listening experience. 

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That average headphone shopper may believe the technology and terminology they'd need to understand to become join the ranks of headphone enthusiasts are just too impenetrable. We're here to disprove that notion. 

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This guide is a primer for the terminology and technology surrounding the topic of modern headphones and how they work. It can be used as the first step toward becoming an audiophile, or as a reference to help you find the headphones that work best for your unique needs. In either case, read on to have some of the most common questions about headphones answered and some of the most common points of confusion demystified. 

Form factors

In this section, we'll cover the three main types of headphones: in-ear, on-ear, and over-ear. 

In-ear headphones

This is the type that most of you are probably familiar with, and the kind you're most likely using on a daily basis. In-ear headphones, or earbuds, rose to prominence alongside early MP3 players. They became truly mainstream as a default pack-in item shipping with just about every smartphone released for several years. More recently, manufacturers have stopped including them with their devices, but the public's preference was already firmly set.

This diminutive style of headphone is easy to toss in a bag or pocket, should be comfortable to wear during anything from commutes to workouts, and can generally be had for the cheapest prices of any of the three form factors we're covering.

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 In-ear headphones come in three general subtypes: 

• Wired: This includes any pair that physically connects to the player, smartphone, laptop, or other device that's providing it with sound. The connectors these terminate in can vary greatly (something we'll cover in our "Connection types" section below), but they all require a physical cable connection to function. 
• Wireless: This type is often lumped in with the third type below, but it originally tended to refer to a pair of earbuds that didn't need to physically connect to a device, but still had a single cable running from one earbud to the other. These remain popular among some athletes and those looking for inexpensive wireless earbuds. 
• Truly wireless: This is the most recent type to be introduced. They require no cables whatsoever, connecting wirelessly, usually via Bluetooth. They charge via their included charging cases. This makes them ultra-convenient for use on the go, unobtrusive (Airpod stems aside), and usually able to last an impressive amount of time without needing external power, thanks to their charging cases functioning as a portable battery pack. 

Pros of in-ear headphones

• Portability: Their size makes them easy to take anywhere and stow in a bag or pocket for use when commuting, taking a run or bike ride, or sitting at your desk. 
• Style: Their small size makes them unobtrusive in public. The presence of certain models in your ears can even be a status symbol for some. 
• Freedom: Earbuds offer a level of freedom either of the larger forms below can't match. Truly wireless options provide completely cable-free use for workouts.

Cons of in-ear headphones

• Sound quality: There are amazing-sounding earbuds out there. But, the miniaturized technology required for them makes them more expensive than equally adept on-ear or over-ear models. Even expensive units still can't match the audio reproduction possible with the larger drivers in other types. 
• Easy to lose: Truly wireless earbuds are especially losable. A loose-fitting bud can easily slip out of your ear and fall someplace it will never return from. 
• Prone to causing hearing damage: Between the air-tight seal many models provide to improve their sound reproduction and the fact that higher levels of volume are often used to compensate for a lack of clarity, cheap earbuds may be responsible for users listening to too-loud audio more often than any other form factor. 

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On-ear headphones

On-ear headphones are the middle child of the headphone world. Like many middle children, they tend to get ignored. Most older readers are probably more familiar with them because they were to walkmen and portable CD players what earbuds were to smartphones. The slim metal headbands and black foam earpads remain a consistent site in every 80s movie. 

However, this form factor actually supports a much wider range of sizes. Some earpads are large enough that they could be mistaken for over-ear headphones. The differentiating factor is that on-ear headphones don't surround your ears. Instead, they sit on your ears, using a headband or, less commonly, an ear hook to stay in place. This provides a middle-ground between the portability of in-ear models and the larger size and sound reproduction of over-ear headphones. 

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As mentioned above, these are the least common of the three form factors. Still, several iconic lines continue to inhabit the space. Koss' Portapro family sits atop almost every "great sound for the price" headphone list, while models like the Grado's SR line have remained on sale for decades thanks to the quality their on-ear drivers provide. 

Pros of on-ear headphones

• Sound quality: Having access to more space than earbuds provides on-ear headphones space for larger drivers (more on these later), offering natural sound, and improved clarity without needing to miniaturize their components. This keeps costs down without sacrificing sound reproduction. 
• Cost: Both the Koss and Grado lines I mentioned above are considered budget-friendly options, with the Portapro typically available for less than $40 and the SR60X selling for less than $100, despite both providing sound quality superior to headphones costing twice or three times as much. 
• Balanced portability: While they aren't as easy to stow as earbuds, on-ear headphones are much harder to lose, offering an excellent balance for the more forgetful among us. 

Cons of on-ear headphones

• Limited selection: As mentioned above, on-ear headphones don't receive as much love as their siblings. This means the selection often consists of models that have been around for many years or models that, to the untrained eye, seem outdated or cheap-looking. 
• Comfort: As the name suggests, on-ear headphones rest directly on your ears. This can make them the least comfortable form factor, depending on how they're constructed. Correctly-designed headbands with adequate padding can lessen the pressure induced by on-ears, but they'll also never be as comfortable as ergonomically designed earbuds or big, pillowy over-ear sets. 
• Limited connection options: This is an extension of the above point. As there's generally a smaller selection of on-ear headphones, there are fewer connection options. The vast majority terminate in a standard 3.5mm connection (explained in the "Connection types" section below), and there are fewer Bluetooth-based options. 

Over-ear headphones

These are the largest form factor, designed to completely surround your ears. They are also called over-the-ear, "cans," or "circumaural," if you're feeling fancy. Whatever moniker you use, they provide the maximum amount of space for the largest drivers. This means they generally have the most natural sound by right of being almost as large as some freestanding speakers. 

Over-ear headphones sit at the very top of the price charts. While there are definitely earbuds and on-ear models that run into four figures, there are multiple over-ear designs that skew into five. Sennheiser's legendary Orpheus, which comes with its own tube amplifier built into a slab of marble has an eye-watering starting price of $50,000, or more if you want them customized. 

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Thankfully, the vast majority of over-ear headphones are nowhere near that expensive and provide exceptional sound for the consumer willing to deal with their tendency to be on the bulky side. This doesn't mean they're uncomfortable, however. On the contrary, I've forgotten I've had over-ear headphones on more often than any other form.

This is also the only form factor to offer two very distinct, purpose-built subtypes: open-back and closed-back headphones. Because of that, we'll be splitting the pro/con section for over-ears into two subcategories. 

Open-backed headphones

Over-ear headphones of this type feature earcups that allow air to freely pass in and out of them. They're the opposite of closed-back models and earbuds that strive to seal in sound by creating an airtight seal around or within the user's ear. The result of this ventilation is a more open-feeling sound that mirrors listening to your audio through speakers. This can also help enhance a pair's "soundstage," or the sensation that the reproduced sound is coming at you from a more nuanced selection of directions than simply left or right. 

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Pros of open-backed headphones

• Natural sound: As mentioned above, the open-backed earcups produce a sound profile that most closely mirrors discrete speakers, or even live music. This is because the soundwaves are allowed to scatter naturally, without ricocheting around in the earcup the way they would in closed-back sets. 
• Comfort: The extra ventilation also means your ears are less likely to get hot, since they're not trapped in an airtight chamber warmed by your body heat. 
• Awareness: Some users want headphones to block out external sounds. Others prefer to hear the world around them. For the latter, open-backed headphones provide a way to keep your ear, literally, open for your kids, co-workers, or even other people on the street. 

Cons of open-backed headphones

• Sound leakage: Open ventilation means any audio, especially at higher volumes, will be audible to anyone within earshot. Be sure to never listen to anything on these you wouldn't want the whole room to hear. 
• Lack of isolation: This is the counterpoint to the final pro above. For those wanting to isolate themselves from the outside world, open-backed headphones are not ideal. They let sound in as readily as they let it out.
• Price: Of all of the form factors and subtypes on this list, open-backed headphones probably have the worst selection of cheap, good-quality options on the market. They tend to exist toward the mid and mid-high end of options, meaning the price for a solid pair often begins well north of $100. 

Closed-back headphones

Closed-back headphones are the precise opposite of those above. Like earbuds, they attempt to seal the sound in, encircling your ear in a (mostly) airtight chamber. This produces a more bass-heavy sound, which can benefit some genres of music or action-heavy videos. However, this seal can also trap heat, and cause issues with unintended resonance from the soundwaves being trapped within the earcups. 

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Pros of closed-back headphones

• Improved bass: Closed-back headphones are usually capable of superior bass reproduction at lower costs and with smaller drivers than their open-backed counterparts. The low-frequency sounds benefit from the tightly-enclosed space, helping closed-back headphones maintain the impact of audio hits like drums or explosions. 
• Isolation: In addition to the active noise cancellation (ANC) available in select models across all of the form factors here, closed-back headphones offer the best passive sound blocking of any form factor. Their seal blocks out outside soundwaves, allowing you to focus on the audio that you want to hear, without it being tainted by external sounds.  
• Privacy: What keeps sound out will also keep it in. Closed-back headphones can provide great sound quality to you, and only you. 

Cons of closed-back headphones

• Heat buildup: Closed-back headphones basically mimic the earmuffs you wear in winter to keep you warm. As such, they trap heat just as well and can get quite uncomfortable in the summer months and in warmer climates.
• Fatigue: Because the soundwaves are trapped inside the earcups with you, closed-back headphones can feel more fatiguing to listen to than their open-backed counterparts. This is caused by the same increased pressure that allows for things like the aforementioned bass reproduction. 
• Less natural sound: We've covered the benefits closed-back designs can provide to low frequencies. But, there are some that find the bass boost they offer to be muffled, or of lower quality than a well-tuned pair of open-backed headphones.

Driver types

Having covered the external size and shapes of headphones, let's take a look inside, at the single most important part of any headphone: the driver. This is the part that actually creates sound. While most people will imagine a tiny speaker, only certain headphones (ones with "dynamic" drivers, specifically) actually use something close to a traditional speaker. 

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The types of drivers in use are actually much more diverse. That said, there are two that remain, by far, the most commonly used variety. Combined, this duo covers at least 99.9% of all models on the market. So, learning about each should let you recognize and understand the technology behind almost every pair of headphones out there. We'll also cover an interesting third, as an example of the less common, exotic drivers out there.

The three types of drivers we'll cover are dynamic, planar magnetic, and electrostatic.

Dynamic drivers 

These are the most common type, the one most are familiar with, and the one that most closely resembles a traditional speaker. They're available across all three form factors, and can be found in everything from the worst-sounding, bargain-basement headphones, to some of the most beloved pairs ever made. Their pricing varies just as widely too. 

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They work by positioning a permanent magnet adjacent to a "voice coil," essentially a tightly-wound length of conductive wire. When current is passed through that voice coil, in the form of an audio signal, it becomes an electromagnet, alternately attractive and repelling the permanent magnet. This creates motion that is used to move a diaphragm, which is a larger surface that pushes around air to create the sound waves you hear. 

The relatively simple technology has been in use since some of the first electrical speakers were produced, and remains one of the most reliable ways to reproduce sound cheaply and effectively. However, well-tuned dynamic drivers can still turn what might otherwise be relatively mundane sound into exquisite audio. 

Planar magnetic drivers

Planar magnetic headphones also use electromagnets to move a diaphragm. However, the entire driver is often just a few millimeters thick, with a diaphragm as thin as a mylar balloon's skin. This makes it possible to move much more air than a dynamic driver could without becoming too larger to fit in even the biggest over-ear pair of headphones. 

Despite its thinness, the necessary internal hardware still produces a headphone that tends to be heavier than its dynamic cousins. But, it also produces drivers that some believe are capable of creating the most natural-feeling sound on the market. Many first-time planar magnetic users often feel like there's a whole wall of sound coming at them, unlike the pinpoint sound sourcing produced by some dynamic headphones. 

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Drivers of this type were almost always found in open-backed, over-ear headphones, as they provided the room to breathe and space that planar magnetic drivers need. However, in recent years, the technology has shrunk to the point that it's made its way into some high-end earbuds as well. 

Whatever the size of the headphone being used, planar magnetic drivers tend to be more power-hungry. This makes them a poor fit for use with your smartphone or laptop. Instead, they usually benefit more than dynamic drivers from being connected to a dedicated amplifier capable of supplying the higher current required to make them sound their best. 

Electrostatic drivers and other exotic options

These are one of the rare, more exotic types of drivers out there. They use a razor-thin membrane floating between two perforated metal plates to produce their sound. As current passes through these plates, a static charge is created that vibrates the nearly weightless membrane to produce sound.

Proponents of this technology claim it's capable of the most natural, "cleanest" sound possible, due to the membrane never physically contacting anything else. Some also believe this cuts down on the distortion dynamic and planar magnetic drivers can suffer from at higher volumes. Whether this is a scientific fact or a simple preference is up for debate. 

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What isn't debatable is the fact that there are considerable hurdles to accessing any electrostatic headphones. Not only do they require a specialized electrostatic amplifier designed specifically for them, but their price also generally skews well into four figures. 

Of course, there are also other exotic technologies that don't cost quite as much, such as the balanced armature drivers found in some high-end earbuds and IEMs (in-ear monitors), or piezoelectric drivers that provide a miniature version of electrostatic technology for IEMs, or even bone conduction drivers that use your own skeleton to transmit sound into your ears. None are likely to ever replace dynamic or planar magnetic drivers, but they can be an interesting technological rabbit hole to fall down, even if you never lay hands on any of them. 

Connection types

Now that we know how the sound's produced, let's talk about how it gets to the headphones in the first place. There are two methods: via a wire, or wirelessly. As you should expect by now, there are also several variations to each of those. 

Wired 

3.5mm connector: This is the most common type of headphone connection. It can be found on almost every laptop and, until a few years ago, almost every smartphone as well. It's essentially the same small "headphone jack" you and your parents have been using for decades, and it continues serving everyone well on everything from dollar store pairs to headphones costing thousands of dollars. 

1/4-inch connector: This is 3.5mm's bigger brother. It's found on lots of higher-end headphones and component systems. It uses a larger connector with more surface area, and is preferred among models that use a "balanced" connection, which relies on discrete circuits run to each earcup. Balanced connections are preferred by some due to their resistance to "crosstalk" or sound that's meant to be played in one ear actually coming through the other ear's driver due to interference. 

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XLR: Another popular choice for balanced headphones. This larger connector is most commonly seen in studio-grade microphones, but also enjoys widespread use among high-end lines like Sennheiser's HD800 series. It provides the most secure connection and uses four completely isolated pins to further prevent any form of interference or distortions across left and right audio channels 

Smartphone connectors: When smartphones shed their 3.5mm ports, many manufacturers continued to offer pack-in headphones that used the phone's data port to receive audio. These unusual headphones included models like Apple's original EarPods, which used the company's proprietary lightning connector, and a bevy of USB-C-based options from Android smartphone manufacturers. As more people moved towards wireless options, these unusual connectors largely fell out of favor. 

Wireless connections

The first thing that comes to mind when someone mentions wireless headphones is Bluetooth. To be clear, that is, by far, the most common protocol for carrying wireless sound. However, it isn't the only method. 

Bluetooth has continued its development in the decades since its original introduction. But, in all that time, it still can't entirely eliminate one pesky issue: latency. This weakness of the technology can add as much as a couple hundred milliseconds (or 2/10ths of a second) of delay to audio. When you're listening to music, this is largely irrelevant; you have no way of detecting the delay. However, when that audio is tied to a visual as well, the delay can be very problematic.

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Bluetooth 5.0 has reduced this delay to the point where it's irrelevant for most video content. Only the most attentive users are likely to notice the minuscule gap between an on-screen character's mouth and their audio dialogue. However, the same cannot be said for gamers.

 In fast-paced games, even a few extra milliseconds can be the difference between life and death. Waiting for an extra 2/10ths of a second to hear enemy footsteps or a starting tone in a racing game? Inconceivable!

Thankfully for the gamers out there, other wireless technologies offer far less latency. The most popular is 2.4GHz wireless. This protocol uses a small USB dongle to connect to a pair of headphones or, more commonly, a headset. The audio from the source is transmitted with little enough latency that it's usually imperceptible to even the most discerning gamers. 

You might be surprised to find out there are some 2.4GHz wireless headphones for comfortable couch listening out there as well, like the Sennheiser RS line. These usually use a base unit that's both a charging stand and a transmitter, providing sound from a stereo, television, or another A/V device. 

Some wireless headphones even rely on infrared light to transmit their sound. These are typically used with in-car entertainment systems or at-home IR transmitters. The benefit of the technology is that any person with compatible headphones can simply sit in a range of the IR signal to hear the sound, without needing to pair their device at all. 

Wrap up

There's no reason not to learn at least a little bit about a form of electronic device that's come to be such an important part of our daily lives. You may find that you'd rather not opt for the same AirPods everyone has, or you may discover that they really are the perfect balance of convenience and quality. 

Whichever way you go, the important thing is that you're well-informed about what options are available to you, how your headphones work, and what the pros and cons of each type of headphone are. A well-informed shopper is most likely to turn into a happy owner.

Hopefully, this guide has given you a deeper understanding of the basic terminology and variables you're likely to run into when shopping for headphones. And, even if you're not currently in the market, maybe you'll impress a friend or two when you point out those sweet new planar magnetic cans your favorite streamer's using now. 

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