This article is about how do headphones work. This is the era of headphones, earbuds, and headsets. Many people tend to regularly use headphones while listening to music or watching movies. The technology has revolutionized so much that you can listen to your favorite songs wirelessly with the help of bluetooth headphones.
If you are curious to know the headphones work, then you are at the right place. We will also guide you about each type of diver function of the headphone. So keep engaged with us till the end of this article to know the answers to your queries.
How Do Headphones Actually Work?
Speakers are the most important part of the headphones and they are made up of three components voice coil, the permanent magnet, and the diaphragm.
Headphones work by converting audio signals/electrical signals to sound waves/mechanical wave energy by acting as transducers. The diaphragm of the headphones moves when the driver reacts to the audio with the help of electromagnetic, electrostatic, or piezoelectric principles.
To know more about the working of headphones, take a look at the given points.
What is Transducer in Headphones?
Transducers are those devices that are used to convert one form of energy into another. In headphones, you will find this conversion turns electrical energy into mechanical wave energy. This conversion of energy depends on the type of driver.
The working principles of headphone drivers include electromagnetic, static, and piezoelectric. It’s important to note that headphones require analog (rather than digital) audio to produce sound. This is because analog audio is actually DC, while digital audio represents analog audio as digital information.
The main conclusion here is that the main feature of headphones is their ability to convert an audio signal into sound. In this way, headphone drivers are like miniature speakers that are worn near our ears.
What is the Science Behind Sound and Audio in Headphones?
Sound consists of mechanical wave energy. Its vibrations are transmitted in the form of audible longitudinal waves through the transport medium (gas, liquid, or solid). The energy of the sound wave causes a change in the local pressure of the medium.
Let’s focus on on-air as a medium because it is the most common source of sound waves for headphones. The sound wave causes a local change in the pressure of the surrounding environment, alternating through maximum pressure and maximum scarcity.
The amplitude of the sound is measured as the amount of pressure change in the medium. The decibel is the most common unit of sound pressure level (dB SPL), although Pascal’s (SI units) and psi/PSF (imperial units) can also be used.
The dB SPL sound pressure level is a logical measure of effective sound pressure relative to a reference value of 0 dB SPL at the human hearing threshold. 94 dB SPL is a common reference point because it corresponds to one Pascal sound pressure.
The frequency of the sound also depends on the frequency at which it vibrates. The human audible frequency range is universally defined as 20 Hz – 20,000 Hz. Hertz is a measure of cycles per second.
In most cases, sounds are made up of multiple frequencies working together. These additional frequencies include harmonics, noise, and other atmospheric sounds.
Depending on the pitch of the musical sound, low notes have a low frequency, and high notes have a high frequency. The wavelengths of low-frequency sound waves are longer, while the wavelengths of high-frequency sound waves are shorter.
Sound carries electrical energy and is basically an electrical representation of sound. With Audio, we can efficiently record, amplify, manipulate and play audio as long as we have the proper storage, amplifiers, processors, and transducers to do so.
A headphone is a transducer that allows the sound to be recreated in the form of sound waves.
Sound is also defined by both amplitude and frequency (hence, phase). Sound waves increase and decrease the local pressure. The “waves” of an audio signal are due to the nature of the alternating current that makes up the audio signal.
How Does Sound Produce in Headphones?
Most of the audio you hear today begins as digital information transmitted from a digital to analog converter (DAC). A DAC converts digital signals into an analog electrical current that the speaker can use to reproduce sound.
For devices made before the digital age, these electrical signals come directly from the analog source media and are transmitted from the amplifier to the amplifier – no digitization is required.
In headphones, as in all amplifiers, a double electric current is transmitted through the wires to the audio coil. When current passes through the coil, it creates an electric field that interacts with the electromagnetic field of the permanent magnet. The difference between the two fields causes the audio file to vibrate.
When the voice coil moves, the diaphragm moves with it. This movement of the diaphragm causes pressure waves (or sound waves) in the surrounding air. These waves are the sound you hear. For louder sounds, the diaphragm moves faster. For lower tones, the diaphragm moves more slowly. The total volume of the sound depends on the relative strength of the electrical signal.
What is the Working of Driver Units in Headphones?
The headphone driver is the power adapter component of the headphones and is ultimately the most important part. The headphone drivers work as part of an electrical circuit that passes the audio signal when the headphone is properly connected to an audio source (MP3 player, smartphone, audio interface, headphone amplifier, etc.).
Headphone drivers are designed to respond to existing audio signals in order to effectively create sound waves that mimic the features of the audio signal. The device stores the digital audio in the form of data by using the digital to analog converter.
The headphones can be designed with a single driver unit for single-ear use. We see this in some headphone designs. However, most headphones are made with two drivers (one for each ear) and are wired to produce stereo sound.
Although most headphones and earphones have dynamic drivers with dynamic coils, there are 5 headphone drivers to fully understand how headphones work:
- Moving-coil dynamic
- Planar magnetic
- Balanced armature
- Magnetostriction (bone conduction)
1. Moving-coil dynamic
A moving coil dynamic driver unit is the most common type of driver unit in headphones. It converts electrical sound signals into mechanical sound waves through electromagnetic induction.
The main components of a dynamic moving coil headphone driver unit are:
- Voice-coil (moving-coil)
- Magnetic structure (magnets + pole pieces)
The sound coil is attached to the diaphragm. This means that when the voice coil is moving, the diaphragm is also moving. The diaphragm is a thin membrane that is always circular, and the voice coil is electrically coiled in a conductive wire (usually copper).
The voice coil is a cylindrical coil of wire that is suspended within a cylindrical cut-out without touching the magnetic structure of the magnetic system. The magnetic structure is designed to keep its north pole inside the voice coil and its south pole outside the voice coil.
The central magnet is a toroidal magnet with its south pole facing upwards and its north pole facing downwards. These key magnets are often made of strong rare earth neodymium but can be made of other magnetic materials.
A ring-shaped pole piece is attached to the top of a central magnet to extend its south pole. To extend the North Pole, a piece of the plate-like pole is attached to the underside of the central magnet, with the piece of cylindrical pole falling upwards.
This format allows the audio file to hang in space. By placing the inner and outer opposite magnetic poles of the coil directly, we increase the strength of the magnetic field in the coil’s coil, thus improving the efficiency of the electromagnetic induction required to convert the audio signal into sound.
All of these components are housed together in a suitable driver unit housing.
Both ends of the audio coil are connected by jumper wires connected to the audio source. It effectively completes a circuit with the audio device when the headphones are properly connected and allows the audio signals to flow through the audio coil.
When alternating current flows through the coil, it produces a coherent electromagnetic field due to electromagnetic induction. The contrast of magnetic field strength and direction mimics an audio signal.
This alternating magnetic field interacts with the permanent magnetic field of the conductor, causing attraction and reversal between the coil and the magnet, causing the sound coil to vibrate in a way that mimics the audio signals.
The Beyerdynamic DT 990 Pro is an example of a dynamic coil headphone.
2. Planar Magnetic Headphones Driver
Planar magnetic headphones transmit energy according to the principle of electromagnetic induction and can also be called dynamic. They have been around since the introduction of the Yamaha Orthodynamic Headphones in 1976. To this day, some people refer to planar magnetic headphones as “orthogonal headphones”.
The main components of planar magnetic headphone drivers are:
- Magnet (in the matrix located on either side of the diaphragm)
- Transmission Marks (Built-in Diaphragm)
The magnets were arranged in rows on either side of the diaphragm. There are many thin magnets on each side of the diaphragm, with space between them so that the sound can pass through the driver unit.
The magnets are arranged in such a way that the space between the magnets on one side matches that of the magnets on the other. The poles of the magnet rotate on the same plane as the diaphragm and are opposite to each other.
Unlike the previously mentioned dynamic coil dynamic motor, which consists of a large conducting coil attached to a membrane, a “dynamic” planar magnetic driver unit has a conducting element built into the diaphragm itself. The conductor coil is very thin and flat, like a diaphragm.
Electrical connection wires are attached to both ends of the conduction signal. When headphones are connected properly, these cables efficiently complete the electrical circuit with the audio source.
When the alternating current of the audio signals passes through the conductive signals of the diaphragm, a corresponding electromagnetic field is created around the diaphragm.
Magnetic rows are arranged in front and behind the diaphragm to represent a specific and focused magnetic field around the diaphragm. This static field interacts with the stimulus zone of the diaphragm. The diaphragm will be magnetically attracted to one line and repelled from the other. As the director of the current changes, so does the speed of the diaphragm.
This results in the movement of a membrane that produces a sound that mimics an audio signal. Since there is a physical distance between the magnets in a magnetic field, sound waves can travel efficiently through the conductor.
The Audeze LDC-4 is an example of a magnetic headphone.
3. Balanced Armature Headphone Driver
The motors of the balanced headphones are dynamic and work according to the principle of electromagnetic induction. These drivers are small in size and are only found in-earphones (especially in-ear monitors).
Balanced drivers are notorious for their limited frequency response, and many of these in-ear monitors require multiple BA drivers to effectively reproduce the full audio range of frequencies.
The BA design has more features than any other type of headphone driver unit. They are:
- Conductive coil
- Drive pin
- Case & sound outlet
Like a moving coil dynamic motor, a BA motor consists of a coil of conductive wire. However, it is not attached to the coil membrane and is not designed to move due to the acoustic signal being applied.
Instead, the coil is wound around the balanced output member (hence the name) between the structure of the magnet with opposite poles above and below the motor.
This is not a coil designed to move, but a member of the motor. This production member is mechanically connected to a movable membrane by a driving pin. While the motor is moving, the diaphragm is also moving.
The enclosure is an important feature that protects the sensitive components of the BA engine. The balanced actuator motors close completely in the case, leaving only a small opening called the sound port, which allows the sound generated by the motor to be transmitted through the air.
Lead wires are attached to each end of the conductive coil, as we’ve come to expect so far. When headphones are plugged in, they allow an electrical circuit between the main wire driver and the audio source.
The audio signal is an alternating current. When this AC signal is applied to the coil, it causes an alternating electromagnetic field in and around the coil and produces high tones.
The balanced armature drivers are also electrically conductive, and when the coil is wound around it, its changing magnetic field is extended to the output member.
As we’ve discussed, the motor is balanced by magnets up and down, and it doesn’t require much force to move. These magnets create an antimagnetic field above and below the motor.
Since the sound signal indirectly changes the magnetic field of the motor, the magnet “pushes” and “pulls” the motor according to the sound signal.
As the motor is moving, the diaphragm is attached to the motor pin and, moving side to side, produces waves of sound.
Therefore, with two degrees of separation, the effect of the audio signals on the coil causes the diaphragm to produce a sound that represents the sound.
The Noise SE535 is an example of a balanced three-motor headphone.
4. Electrostatic Headphones Driver
As the electrostatic headphones name suggests, electrostatic speaker drivers do not transmit energy through electromagnetic induction but work on the principles of static electricity.
These electrostatic headphones are quite unusual but can deliver incredibly accurate results and pure sound quality.
To function properly, electrostatic headphones require special amplifiers that amplify the voltage of the audio signal to peak levels. These amperes often provide the required DC twenty-two volts for the conducting diaphragm.
So what are the basics of an electrostatic headphone driver? They are:
Like a planar magnetic driver, an electrostatic driver consists of a diaphragm sandwiched between two perforated “plates”. This is where the similarities end.
The diaphragm of an electrostatic driver is conductive and is designed to carry a constant electric charge. The stators at the front and back of the diaphragm are perforated plates designed as a kind of parallel plate capacitor. The diaphragm rotates around the electrostatic driver frame and is electrically isolated from the stator plates.
Aside from the housing (which includes the necessary damping), the planar magnetic driver unit largely summarizes the physical components of a basic electrostatic driver unit.
To function properly, however, the driver unit must be connected to a special subwoofer.
These amps vary in their design, but almost all of them include, at some point, a step-up transformer that effectively increases the signal voltage by simultaneously releasing current. Of course, there are active amplifier components (including tube and/or transistor circuits), but the converter is a common component that amplifies the voltage to a useful level.
First, the amplifier picks up the audio signals and amplifies the voltage. Headphone signal strength from 100 to 800V is normal for electrostatic headphone drivers to operate. Well, this voltage level will fry every dynamic headphone driver.
The bias voltage across the diaphragm of an electrostatic motor can be within the same range.
It is important to note that unless the current is low due to the excessive resistance of electrostatic motors, the voltage can be incredibly high.
The amplifier effectively increases the voltage and decreases the audio signal current so that the diaphragm can operate correctly while providing 22 volts to the driver.
The amplifier output is connected to the stator plates of the electrostatic motor. The electrical circuit is complete with stator plates that act as a capacitor.
Because the high voltage audio signal applies a positive charge to one stator plate, it also applies an equal but opposite charge to the other stator plate.
The positively charged diaphragm, at any time, attracts attention to one of the stator plates and repels the other. This attraction/reversal is reversed with the alternating current of the audio signals change. Therefore, the diaphragm will move according to the sound signal and generate sound that mimics the sound signal.
The fifth and final type of headphone driver that we will be discussing is the relatively unknown driver for magnetic stenosis.
This driver works on piezoelectric principles and focuses on moving our skull and inner ear to create a sense of hearing, rather than creating sound waves for our ears to hear. Our “skull vibrations” may seem intense, but our inner ears convert those vibrations into sounds all the time.
Besides the bone transmitter in bone conduction headphones, we have a piezoelectric crystal that accepts the audio signal from the source and vibrates accordingly.
When this crystal is pressed against our jaws or cheekbones (or other bones in our head), it transmits its vibrations to our inner ear, which in turn converts these vibrations into electrical signals that our brain calls sound.
Aftershokz Aeropex is an excellent example of aerobic headphones for orthopedic implants.
What is the Function of Wireless Headphones?
Unlike wired headphones, wireless headphones work by receiving audio signals from wirelessly connected audio sources. There’s not much difference between standard wired headphones and wireless or Bluetooth headphones function – the process is almost identical.
More specifically, the wireless receiver inside the headphones receives a wireless audio signal (embedded in the radio signal or an infrared signal called a carrier signal) from the transmitter. It decodes audio from wireless carrier signals and uses them to drive headphone drivers and produce good sound quality.
Wireless headphones can provide more comprehensive control over your music. While some wired headphones allow you to play and pause your content, many Bluetooth models allow you to adjust the volume, pause or play music, and skip or rewind the track. Some headphones work by allowing you to hire digital assistants like Siri.
For wireless headphones to work, you will require battery power. This means that your wireless headphones will not work if they run out of juice.
What is the Function of Noise-Cancelling Headphones?
When we talk about noise-canceling headphones, we are talking about headphones with active noise-canceling circuits. This is because all headphones have some degree of ambient noise cancellation as they actually block certain sounds from entering the ear.
Active noise-canceling headphones measure the amount of noise using a built-in microphone and process the microphone signal into an anti-noise signal that is then incorporated into the headphones’ essential audio that is transmitted to the driver.
In suitable noise-canceling designs, each earpiece has its own microphone and an active noise circuit that changes the phase and amplifies the microphone signal.
Feedforward ANC headphones have microphones on the outside of the ear cups, while feedback ANC headphones have microphones inside the ear cups. Hybrid systems in headphones work by using microphones in and out of the ear for best results.
Closed-back surround headphones offer the best passive noise cancellation and are the best candidates for improvement through active noise cancellation. This bluetooth headphones work with the ambient noise effect.
The Bose 700 is an example of noise cancelling headphones. In addition to active noise cancellation technology, the Bose 700 is also wireless (Bluetooth). They have dynamic movable electromagnetic coil motors and a closed-back contour fit.
Comparison Between Wired and Wireless headphones
|Wired Headphones||Wireless Headphones|
|Wired headphones are easier to connect with other devices.||Wireless headphones are a little bit tricky and can be confusing while connecting with other devices.|
|You are bounded to stick with the device that you have connected.||You can wander around as long as you are within the range of a bluetooth device.|
|The audio in wired headphones is converted to digital audio to analog output.||The audio is sent to the headphones and then converted to the analog signal.|
|They provide sound without lossy compression.||They provide sound quality with lossy compression.|
|Some of the wired headphones work by giving you limited control.||Bluetooth headphones work by offering you more controls over your music.|
Frequently Asked Questions
What is the science behind headphones?
Inside the headphones, the motor effect is used that contains small loudspeakers. The variation in electric current moves the magnet and creates sound waves by pushing the compressing air.
How do we hear sound through headphones?
We hear sound through headphones with the help of a transducer. Many headphones use magnets and a voice coil that moves the diaphragms back and forth and results in creating sound waves.
This was all about headphones work. I’m sure after reading this complete guide you must have understood how do headphones work. Headphones are becoming increasingly technological, and will continue to be so – however, the working principles of the sound will remain largely the same.
So what do you think about how headphones work? If you have any questions about how do headphones work, feel free to let us know in the comments section below.