How Do Headphones Work?

Headphones are one version of portable speakers, together with earphones, and buds they’ve become synonymous with our tech experience. They blast our favorite tunes, allow us to listen to the latest podcasts without the rest of the subway having to join in, and they allow for some crazy 8D sound experiences. But just how do headphones work?

The answer –  while they’re technological masterpieces with teams of people working to improve the technology day after day, in essence, they’re just tiny speakers taking electrical signals and transforming them through a voice coil (I know, cool right) into Jack Johnson’s sweet tunes.

It’s a very simple, yet complicated, process. The 1’s and 0’s that make up your audio file send signals, in the form of fluctuating electrical currents, through your headphone cord to the drivers in the speakers. This signal is passed through the voice coil and generates a magnetic field. A fixed magnet inside the driver attracts or repels the coil depending on the alternating current. The voice coil, in turn, is attached to a lightweight diaphragm (pronounced die-a-fram) in the driver. As the coil moves back and forth, thousands of times per second, it changes the air pressure just so to produce sweet, sweet sound waves for our enjoyment. I know, unbelievable – but that’s the condensed version, it gets even more interesting.

All headphones weren’t created equal, and if you’d like to find out what’s the difference, continue reading.

Headphones Are Basically Just Tiny Loudspeakers, But…

To understand the inner workings of your headphones, you could simply imagine them as small-scale loudspeakers. Their purpose is the same, to take electrical signals and transform them into corresponding sound waves.

It is a little bit more complicated than that though, the engineers who design these tiny little speakers have to take into consideration the close proximity of the speaker to the ear. This requires much smaller input levels; we’re talking milliwatts instead of watts.

This is essentially the main difference between your loudspeakers and your headphones, the size. In contrast to loudspeakers that have to deal with producing sound for rooms, halls and open-air concerts, your headphones should produce enough sound for your ears only.

So, while they are very similar, tinier versions of the same thing, the tech needed to make them do what they do are slightly different.

When it comes to the protective casing, there is a small difference between loudspeakers and headphones. The loudspeaker box (or enclosure) is there to amplify the sound and to protect the speaker. Similarly, your headphone’s “cover” is made to amplify, protect, but also to fit. These are wearables, and the demand is comfort.

To amplify sound, loudspeakers generally have an opening at the front and the back; this allows the free movement of air to generate the best sound. With headphones there are two different types, closed-back and open-back. Open-back often produces the best sound, and you’ll find them being used in recording studios. However, they can be less discreet. Someone who wants to listen in private should rather go for closed-back noise-canceling headphones.

What Are the Major Headphone Components?

There are three very important components in your headphones. Different types of headphones may have additional bits and pieces, but without these three, no sound is ever coming out:

■ The Magnet

Magnets are at the core of your headphones. Two tiny magnets, one fixed and one electromagnet that moves, cause the coil to move. This movement is essentially what causes the sound to be produced.

■ The Voice Coil

The coil is fed with electrical signals; this causes the coil to become more or less magnetic depending on the current. The coil, in turn, is attached to the diaphragm (think about your own diaphragm that allows air to move in and out of your lungs), and as the coil moves, the diaphragm moves.

■ The Diaphragm

The diaphragm is a thin, semi-rigid membrane that is attached to the coil. When the coil moves, the diaphragm moves, creating vibrations and producing sound. 

Housed inside the driver assembly, these three parts are responsible for generating the sound. Understanding exactly how the driver works can be complicated.

How Headphone Drivers Work

The driver is like the brain of this whole operation. When an electrical signal is passed through the cord and enters your headphones, it first reaches the driver unit.

There are three main types of drivers used in headphones: 

• Dynamic driver
• Planar magnetic driver
• Electrostatic driver

The most common driver used in headphones is the dynamic driver.

■ Dynamic Driver Unit (Moving Coil Drivers)

The dynamic driver unit is one of the most common drivers and also the cheapest. It uses three major components to work: the permanent magnet, an electromagnetic coil, and a diaphragm.

The dynamic driver unit uses electromagnetism and magnetism to create movement, which in turn produces sound.

The coil is magnetized by the fixed neodymium magnet, turning the coil into an electromagnet. Once the coil receives electrical signals from the audio file, it creates a magnetic field. The flow of the current determines the push and pull of the magnet.

This creates rapid movement, backward and forward, in turn, pushing and pulling the diaphragm to which the coil is attached. The air around the diaphragm is displaced, producing sound. The more air is displaced, the louder the sound.

Due to the friction, this creates, dynamic driver units are great for creating bass sounds. There are, however, drawbacks. For one, audio is easily distorted. This can be fixed with some great engineering, as it often is in some of the high-quality headphones.

■ Planar Magnetic Driver Unit

While the planar magnetic driver unit is similar to the dynamic driver unit in many ways, there are notable differences.

First of all, instead of using magnets to move the coil, wiry magnetic conductors cover one side of the diaphragm itself. Furthermore, an array of magnets behind the diaphragm are used to pick up the electrical current as it passes through the conductors. As the electrical signal moves in and out of the conductors, it changes the magnetic field, causing the diaphragm to interact with the magnets, causing vibration and ultimately producing sound.

These drivers are mostly used in high-quality open-back headphones. The diaphragm is often bigger and due to the multiple magnets, a lot heavier. These headphones aren’t exactly your jogging set. At home, or in a recording studio, they produce clear sounds with almost zero distortion and good bass response.

■ Electrostatic Driver Unit

Lastly, we have the electrostatic driver unit, often considered the holy grail of headphone driver units, the tech is impressive.

While in other drivers, the coils are usually moved by magnets, and that in turn causes the diaphragm to move, whereas, with this driver, the diaphragm itself is the moving part. The diaphragm is made of a thin sheet of electrically charged material, which is placed between two oppositely charged conductive plates. As the electrical signal is passed through the plates, the electrically charged diaphragm vibrates, displacing air and producing sound.

As the tech that backs this driver is quite scarce, it also comes at a pretty price. They are mostly used by professionals and are better suited in a studio for occasional use. However, the sound quality is insane, and as with all technological advancements, we can only hope that this will soon be the future for all headphones.

How In-Ear Headphones (or Earbuds) Work

These little buds work in much the same way as headphones, the biggest difference again being the size. All the same components are there, just much smaller, and for good reason, it all needs to fit into your ear.

What’s great about earbuds is that even if the parts aren’t exceptional quality, you don’t need to produce a lot of sound as it’s only traveling the distance of your ear canal. They usually have a teardrop shape allowing for a snug fit in the ear. The quality is usually clear, and any external sounds are blocked out by the earbud.

Most earbuds are protected by a hard-plastic casing and are considered closed-back earphones. Some may have vent holes that allow some outside noise to come through.

The mechanics are very similar to the larger headphones. An electrical charge is sent through the cord and enters the driver. In the driver, the coil gets magnetized and moves with the magnetic pull and push of the signal. As the coil moves, it pulls the diaphragm, producing sound waves.

Earphones are easier to transport than headphones because of their small size. Though headphones can offer better sound, earphones definitely win in terms of ease of use. Easy to pop into a bag and pull out when needed. When it comes to comfort, headphones often win. Earphones, though small, sometimes just don’t fit your ear. Luckily, there are hundreds of designs to choose from, and you get your perfect fit eventually.

How Over-Ear and On-Ear Headphones Work

Now that you have an idea of how loudspeakers work, you can apply that knowledge to over-ear headphones. While we don’t recommend trying this at home, we’ll quickly open up a headphone and talk you through all the parts.

With headphones, the very first bit you notice is the headset and the poofy ear covers. They look great, but that’s not where the magic happens. Opening up the pads, you get closer to the inner workings of your headphones.

The driver, battery, and everything else is housed inside the headphone (both over and on-ear) enclosure. The main part that generates the sound is the diaphragm, as we discussed earlier in this post. The diaphragm can also look like a cone, and no surprise, then it’s called a cone.

As the diaphragm is pushed and pulled, it produces sound. The pushing and pulling action can be produced differently, depending on the driver unit.

There are two units that offer the best quality sound. The Planar Magnetic Driver Unit is an upgrade to the traditional dynamic driver unit. Instead of the usual magnets, this rectangular shaped driver unit houses a diaphragm that is covered with electric conductors. This then gets pushed and pulled by an array of surrounding magnets. The diaphragm receives the electric signal, changing its charge and causing the vibration. Genius.

The next favorite has to be the Electrostatic Driver Unit. This little powerhouse is the most unique design on the market. The diaphragm is as light as air, and the material it is made from is electrically charged material. The diaphragm is set between two perforated metal plates, and when an audio signal is directed to these plates, it causes a magnetic pull that uniformly vibrates the diaphragm. This produces the smoothest sound with the least distortion of all the drivers.

In essence, when you play music through your earphones, it’s all-electric signals, magnets, vibrations, and displaced air that eventually gets you to the sweet sounds you want to hear.

How Open-Back Headphones Work

Open-back headphones have the same inner workings as normal headphones, but the difference comes in with the casing. Instead of a closed unit, the unit is open on both sides, allowing the free flow of air, giving better sound and acoustics.

This design is quality driven and often more comfortable. It’s a great option for those who work with sound, and who need to wear their headphones for extended periods of time.

Due to the open back, comb filtering is prevented (sound engineers sing hallelujah). The open-back generally has bigger cushions, for superior comfort.

The back of the headsets is open, preventing comb filtering, allowing sound to travel both ways easily and normally with little isolation, while the headband exerts very little pressure on your head.

While they offer all these added benefits, they are often much lighter than cheaper models, due to higher quality materials being used.

Some of the drawbacks of open-back headphones is that noise cancellation is virtually impossible, making them less than ideal for noisy areas. Next, if you’re a recording artist, some of the noise could bleed into your mic if you increase the volume too much.

How Do Noise-Canceling Headphones Work

We all know about the wonders of noise-canceling headphones, but how exactly do they work?

First of all, we need to understand there are different levels of noise-canceling tech out there. Essentially, there are two types: passive and active.

■ Passive Noise-Canceling Headphones

These are very similar to something like earmuffs, acting as a physical barrier, preventing any external sounds from reaching your ears.

■ Active Noise-Canceling Headphones

While still offering a physical barrier (improved though to eliminate specific high-pitched sounds), active noise-canceling utilizes tech to allow your microphone to pick up any low-frequency noises and neutralize it before it reaches the ear. Amazing, I know.

Here’s How Active Noise Cancelling Works

Active noise-canceling is essentially just smart tech. You have a microphone that picks up any exceptionally high- or low-pitched sounds. These are then analyzed by an electronic system, which identifies any unusual patterns.

Using this info, whenever your headphones pick up these noise wave peaks, they will cancel out the vibration. Your headphone speakers create an anti-sound wave, neutralizing the ambient noise.

Noise-canceling headsets aren’t perfect though; they can only block around 70% of the outside noise (not bad though). They are perfect for places with low-frequency noise, such as open offices, public transport, and planes. If you’d like to find out more about noise-canceling headphones, I recently wrote an article that goes into detail.

How Wireless Headphones Work

Wireless headphones are great, they give the ultimate freedom – but how do they work? The mechanics are basically the same in terms of how the sound is produced, but how does the electric signal reach the driver unit? In comes modern wireless technology – the audio signal is actually sent through wireless technology, such as Bluetooth, radio frequency (RF), or infrared (IR).

How Bluetooth Headphones Work

Bluetooth headphones can play music wirelessly. They connect through radio waves to Bluetooth-enabled audio devices. You can use your Bluetooth Headphones with your smartphone or any other smart device. Bluetooth Headsets can pick up the radio waves up to 50 meters away.

As soon as you turn on the Bluetooth on your smart device, you will pick up the Bluetooth headphones. The headsets do need to be in discoverable mode to enable the pair function, but once you pair the devices, you won’t have to do it again. You might need to enter a password to pair successfully; this can be found in your user manual or in your Bluetooth settings on your smart device.  Interestingly, Bluetooth devices usually connect over a 2.4 GHz radio band, which is license-free.    

How RF Headphones Work

RF Headphones work in a very similar way to Bluetooth headphones, the one major difference being that they transmit on different frequencies. RF headphones make use of 900MHz to 3.2GHz frequencies. With RF Headphones, you’ll be able to still pick up the frequency at around 90 meters.

Use is simple; just connect the transmitter to your smart device using the AC adapter and switch it on. The RF headphones and the transmitter should pair automatically. The transmitter should display a blue light once the devices are paired.

RF Headphones usually work best for TV’s, you simply plug in the adapter and forget about it. Perfect for gamers and late-night binging. 

How IR Headphones Work

Infrared isn’t as great as Bluetooth or RF, because sadly you have to maintain a line-of-sight. So, you can’t move around freely while listening to your favorite podcast or tune. The technology is pretty much the same, with a transmitter and a receiver, but the frequency doesn’t reach very far (max 10 meters). Essentially, it’s the same technology used in your TV remote.

You get two types of IR wireless headphones – single channel and dual channel. Single-channel can connect to one audio signal only, while dual-channel can handle two. IR headphones differ, and you’d have to confirm the frequency of infrared you require.

Similar to RF headphones, IR headphones often come with an IR transmitter that you connect to your audio source.

How Bone Conduction Headphones Work

This is really cool, and I’m sure most people would probably pass on buying bone conduction headphones, but for many with hearing impairment, it can be a godsend. So how do bone conduction headphones work exactly?

Bone conduction headphones work by decoding sound waves and converting them into vibrations that pass through your bones (cheekbone or upper jaw) and can then be received directly by the Cochlea, bypassing the eardrum.

One negative of hearing through your jaw (as cool as that may be) is a different, poorer quality sound. It’s not bad; it’s just not great.

Interestingly, the vibrations and frequencies created by bone conduction headphones still create a sound that can be heard by other people. Without the usual snug fit of the ear, the sound is even more likely to be heard by others.

How Headphone Jacks Work

To get the sound, you need the electric signal. In the end, headphones are a complete circuit, a loop of wires with current running through it. This electric current in the loop then interacts with a permanent magnet that then moves the diaphragm, displacing air and tada – sound.

But the signal needs to come from somewhere. That’s where the jack comes in. The current comes from your device, and via the jack flows through the cord into the driver unit of the speaker, setting off a sequence of events that finally result in sound.

But it all starts with the jack. The jack makes everything easy and simple, no loose wires to connect, just plug and play.

A headphone jack serves as an electrical connector, which is normally used for audio signals. It requires between two to four contacts to work, and there are numerous designs – just think Apple.

When your jack has two contact points, it’s called a TS connector, three contact points is called a TRS connector, and four contact points is called a TRRS connector.

The T refers to the tip, the R refers to the ring, and the S refers to the sleeve. A TS connector carries only a mono signal, while a TRS connector carries two signals, and a TRRS connector carries three signals.

Headphone jacks come in different sizes, and the most common are: 6.35 mm, 3.5 mm, and 2.5 mm. The most common jack size would be the 3.5 mm jack.

Typically, the TRS headphone jack on stereo headphones only carries the left and right channel signals when connected to an audio source, while the TRRS headphone jack on stereo headphones carries the left, right, and the microphone signals when connected. By allowing back and forth communication, TRRS is the most popular on the market. 

How the Headphone Wires Work

Headphone wires are not something we often think about, but neatly encased in protective rubber lies 6 wires, all essential in carrying your sound waves to your ears. 

The six wires that connect to your TRRS jack are:

To add strength to your cord, there is a synthetic core added in between the wires.

Headphone cables have come a long way – and this is evident in the cables. Your headphone has cables that power a control panel for play, pause, change track, and volume control.

There are several different headphone cables on the market, including:

• Optical cables: For extra fast transmission, some cables are designed from optic fiberglass.
• Regular cables: Ordinary copper wire, covered with protective plastic material. These are the most common.
• Flat tangle-free cables: While also making use of copper and covered with protective plastic, these cables are flattened to prevent tangling.
• Coaxial cables: Coaxial cables have a copper center, plastic cover for insulation, AND additional fabric covering. Very durable as well as high performing.
• Fabric braided cables: These are considered hybrid cables and make use of different materials for conduction and insulation.High quality and durable.

It can be hard to choose the right headphones, but having all the information, knowing the differences, and why each is unique in its own way will make the process easier. Your headphones should complement you, if you use them for work, you should choose the best quality, if you like running with your headphones you’ll need great wireless capabilities, comfort, and durability. It is possible to get the perfect headphones to suit your lifestyle.