AMATEUR TO AUDIOPHILE: HOW DO HEADPHONES WORK?

Written by Asha Kalsi 

Curious as to how exactly your headphones work? We’re here to break it down! 

We all use headphones regularly, but have you ever stopped to think about how they manage to produce the amazing sound that lets us enjoy our podcasts, music, and TV shows? It's quite impressive how these compact little devices deliver such an immersive listening experience. Let's take a moment to explore the fascinating technology behind these essential gadgets! 

Small but Powerful: The Essentials  

Don't let their small size fool you, headphones have some sophisticated tech inside. At their core, they serve as transducers, transforming electrical energy into the audio signals that bring our favourite tunes to life in the form of sound waves. This process is commonly referred to as "audio reproduction". So how do they do it? Headphones consist of two key components: drivers and earpieces. The drivers take on most of the heavy lifting, creating vibrations that generate the sound waves we hear, while the earpieces play a crucial role in amplifying and directing these waves to reach our ears with precision. It's fascinating how these seemingly simple devices work together to deliver the immersive audio experience we all enjoy! 

How do Headphones Receive Sound? 

Audio signals describe the reproduction of sound in the form of AC voltages. In order to convert audio signals into the songs we love, there needs to be a means of connecting the audio source to our ears. 

• Wired Headphones: The process starts just before the headphone socket in the source device, which contains amplifiers (to make the sound louder) and digital-to-analogue converters (DACs). Headphones are inherently analogue, while most modern audio devices are digital, making this an essential first step. They typically receive unbalanced stereo via TRS or TRRS cables to drive each of their drivers separately. 
• Digital Headphone Cables: With the decline of devices with 3.5mm jack compatibility, headphones with USB-C or lightning cable connections have risen to meet the demand. Unlike wired headphones, these make a digital connection with the audio source, then there is a tiny amplifier and DAC inside the plug on the headphone cable to convert the digital audio into the real AC voltages that allow the drivers to function. 
• Wireless Headphones: Wireless headphones, unlike their wired and digital counterparts, don't make a physical connection with the audio source. So, how is the audio signal transferred? Because they don't make a physical connection, audio signals are encoded into carrier signals, which consist of either infrared or radio frequencies. The wireless transmitter or audio device sends the signal, usually via Bluetooth, using a digital language (or Codec) that the receiver in the headphones can understand. The wireless receiver in the headphones interprets this Codec and converts it (again via a DAC) into an AC, audio signal which is fed into the drivers. 

What’s Driving Your Sound? 

We mentioned previously that it's the drivers that are responsible for converting the electrical audio signal into the sound we enjoy. But how does this conversion happen? 

Different types of drivers achieve this through different means depending on the type of audio device they're used in. When it comes to the consumer headphones and earphones we're all familiar with, there are two main types of drivers used: dynamic drivers and balanced armature drivers. 

• Dynamic drivers, also known as moving-coil dynamic drivers, convert electrical signals into sound waves using a moving coil, magnets, and a diaphragm. When an audio signal is applied, the moving coil is turned into an electromagnet which pushes and pulls against the fixed magnets in the back of the driver, and causes the coil to vibrate in a manner that reproduces the vibrations of the audio signal. This recreates the sound the audio signal is transmitting. Over-the-ear headphones commonly use dynamic drivers because they offer a rich and full sound experience. 
• Balanced Armature Drivers, on the other hand, employ a tiny armature suspended between two magnets to convert electrical signals into sound waves. Although more complex than dynamic drivers, they operate on similar electromagnetic principles. In addition to magnets, a conductive coil, and a diaphragm, balanced armature drivers incorporate an armature, drive pin, and a protective case to allow for a more compact means of recreating audio signals. Unlike dynamic drivers, the coil responsible for generating the electromagnetic field remains fixed. Instead, it is wrapped around the armature, which is balanced between the north and south poles of the magnets. When the audio source applies current to these drivers, the armature moves in response to the magnets' push and pull. This movement, facilitated by the drive pin, directly manipulates the diaphragm. Similar to dynamic drivers, it's this movement that generates the sound waves. In-ear headphones typically employ balanced armature drivers, delivering a more detailed and nuanced sound. 

In addition to these well-established headphone drivers, high-end audiophile headphones are beginning to incorporate other types of drivers. These include planar magnetic drivers, electrostatic drivers, and bone conduction drivers. 

• Planar magnetic drivers have a very thin flat diaphragm that has a wire that cris-crosses the surface of the diaphragm, and pushes and pulls against a fixed magnet when the AC signal is applied to the wire. 
• Electrostatic drivers, which are currently pretty uncommon, rely on specialised amplifiers to boost the voltage applied to the electrically insulated diaphragm, causing it to vibrate according to the audio signal, effectively recreating it. 
• Bone conduction drivers utilise piezoelectric crystals which vibrate our skulls in response to the audio signal. This allows the signal to reach our inner ears to create the sensation of hearing, without producing traditional sound waves for us to hear. 

By employing these different types of driver technology, you can tailor your audio experience to meet your music preferences and enjoy your favourite music in the best possible way. 

What about Bonus Features? 

In addition to the fundamentals, extra features may be included in the design of some headphones to enhance your listening experience in various ways. 

• ANC: Active Noise Cancellation is a feature that is increasingly common across headphones of different price ranges. It is designed to actively block out background noise by producing sound waves that counteract the detected ambient noise. This technology utilizes small external microphones to accurately capture the background noise and generate anti-noise signals, resulting in a more immersive listening experience. You can learn more about how ANC works here.
• EQ: Equalization is a feature found in specialized headphones that allows you to adjust the loudness of specific frequency ranges. By dividing the sound into multiple separate frequency bands, headphones with EQ capabilities provide virtual sliders that enable you to increase or decrease the volume of each band. This customization allows you to tailor the levels of low, mid, and high-pitched sounds in the music, allowing you to emphasize the aspects of the music that suit your personal preferences. 
• IP Ratings: Headphone IP ratings indicate the numerical level of water resistance they are designed to have. The ratings range from IPX0, which describes headphones designed without offering water resistance, to IPX9, which describes headphones that can safely withstand steam cleaning and high-pressure washing. For consumer headphones, the standard IPX4 rating describes their ability to withstand splashes but not submersion, providing a level of protection against accidental liquid contact. Water protection is an important consideration for headphones, particularly if you anticipate using them in environments where water exposure may occur. 

Now that you’re armed with the technical knowledge of how your headphones work, why not check out our amazing range at Mixx? Find the perfect pair today!