TYPES OF HEADPHONES - AN INTRO

Ever wondered why headphones come in various shapes and sizes? Why some cost less while some cost a bomb? Some require an amp while some don't? Well, in this post, i have discussed the different types of headphones from various brands in terms of their pros and cons with their working principle.

Headphones can be classified on the basis of -

I. Earcup Design

II. Connecting Technology

III. Type of Driver used

Let's jump into the details -

I. Based on Earcup Design -

1. Closed back headphones

The Senheiser HD280, as you can see the outer casing is completely closed.

Probably the most commonly seen type of headphones used by people in general. The outer casing is completely closed which means there will be no/minimum sound leakage though it does cause heating up of headphones, making the ears feel uncomfortable after prolonged usage. The noise isolation is also better than open back headphones.

2. Open back headphones

The Beyerdynamic DT990 pro which comes with an open back design, widely used in studios for monitoring purposes.

They're generally used by studio professionals/audiophiles. Regarding the design, the outer casing usually consists of perforations or a mesh type design, which will allow the free flow of air & sound, providing the user a more "wider soundstage" but it also means that there will be some considerable amount of sound leakage due to which people near you can hear what you're listening to.

Bottomline - if you're going to use it in an isolated environment like a studio or inside your home then you can go definitely go for the open back ones.

3. Semi open back headphones
 

The AKG K240

Well, the semi open back headphones as the name suggests has a mixture of properties i.e properties of closed back and open back. They're mostly used for critical listening by studio professionals.

4. Supra-aural headphones

The Grado SR325

These are otherwise known as on ear headphones as they literally sit right on your ears (because the size of the earcups aren't big enough to enclose the ears). They are quite portable as they don't weigh much. The downsides are that, one, since they rest on your ears, after prolonged usage the pressure builds up which leads to some discomfort and two, they don't isolate the ambient noise well enough, this becomes a problem when you're in a public space.

5. Circum-aural Headphones

The Sony MDR7506, with earcups big enough to enclose the ear

They are also called as over ear headphones as the earcups are big enough to enclose the entire ear giving the user a much better sounding experience as they isolate the ambient noise. Nowadays, these type of headphones are the most commonly used type due to its comfort and relatively better noise isolation.

II. Based on connecting technology -

1.Wired

As the term suggests, these type of headphones usually transfer the audio signal via wires that are connected to the source.

2.Wireless/Bluetooth headphones -

These are the type of headphones that make use of the bluetooth technology to transmit the audio signal. A big advantage is that they solve the problem of the wires getting tangled. There are also wireless headphones that don't actually use bluetooth connectivity but they're extremely rare to be found in the consumer segment.

III. Based on the driver technology -

Before we can get started with the different types,

What's a headphone driver ?

It is basically an electromagnetic component which converts the incoming electric signal to a sound signal that is perceivable by the ear. It comes in various sizes & in some cases multiple drivers are used to reproduce the sound more accurately.

Now, let's jump to the different types -

1. Dynamic or Moving Coil

Most headphones use the Dynamic/Moving Coil driver as it is cost effective.

This type of driver is the most commonly used as it is less sophisticated and hence the cost of manufacturing is naturally less compared to other driver technologies.

Working

Consists of 3 parts - A magnet, voice coil & a vibrating diaphragm.The magnet is attached to the frame of the headphone while the voice coil is suspended in the magnetic field of the magnet, which is attached to the diaphragm.

The moment the electric signal flows, the magnet magnetizes the voice coil which in turn creates a magnetic field of its own which causes the diaphragm to vibrate (displacement of air), this process creates the desired sound waves. The bass produced is directly proportional to the amount of air displaced in the process.

The vibrating diaphragm

2. Balanced Armature

The Shure SE846 which comes with 4 drivers to increase the sound quality by assigning certain frequency range to a particular driver.

Balanced Armature drivers are usually found only in IEMs (In-Ear Monitors) due to their small size. It has much better efficiency compared to other drivers on this list.

Working

As seen above, the driver consists of a coil surrounded by magnets on either side. The armature is positioned in such a way that the net pressure exerted on it is zero, hence the term "balanced". When the electric signal passes through through the coil, it magnetizes the armature in such a way that it starts to rotate in one direction thus resulting in the diaphragm to move continuously & produce sound.

3. Planar Magnetic or Orthodynamic Driver

The Audeze LCD-3, the company Audeze specializes in manufacturing planar magnetic headphones.

These type of headphones can get pricey but at the same produces extremely good sound, probably the best due to its unique technology (which is discussed below).

Working

Different sections of planar magnetic headphone. source

Here, a thin diaphragm is sandwiched between two strong magnets instead of a coil like in the case of dynamic driver headphones. The similarity is that both use magnetic fields to produce sound. The diaphragm has wire pattern running over it. When current passes through the wire, it sets up an electromagnetic field which interacts with the existing magnetic field which makes the diaphragm move back & forth which ultimately results in the production of sound waves. When the diaphragm moves back & forth, it has to move uniformly for which the magnet need to be big & efficient, due to this the headphone naturally becomes heavy and in most cases require an amp.


4. Electrostatic Driver

The Stax LR-300 with an amp

This category of headphones are probably the most expensive among the entire list. Naturally, they aren't seen as often as the other types in the market.

Working

Here there is no magnet involved in the reproduction of sound from the electric signal. Instead, it uses the principles of static electricity. It consists of a thin diaphragm suspended in between two stators. When the current is passed to the stators there is an alternate current polarity which is induced into them. This varying polarity causes the diaphragm to move back & forth forcing the air to be displaced through the perforations & this continuous displacement of air due to the varying electric field is what causes the sound to be produced.

5. Magnetostriction or Bone Conduction

Bone conduction headphones by Aftershokz

It is the result of technological surge that has occurred in the recent past. In this type, there is no direct contact with the ears instead the sound waves are conducted by bones i.e the bones present in the skull. The driver basically converts the sound signal by sending in the vibrations. Though this type of driver isn't as good as other drivers of in terms sound quality, it is very helpful for the people who are deaf / have hearing loss as it lacks the role of eardrums in the process.


Hope this was helpful & informative to the readers. In my upcoming blogs i'll be talking not only about audio tech but also about electronic music, so stay tuned!

Sources -
Types of drivers

Planar magnetic tech