Insight - How Ear Phone works

                Insight - How Ear Phone works

Ear phones/Earbuds have been assisting mobile gadgets since the invention of walkman. Though they account for hardly a few percentage of the cost of the entire device but their evolution over the time has never been an easy challenge for the engineers. Shape, size, comfort and sound quality are the key parameters while designing an earphone.  From morning walk to making long journeys pleasant, ear phones cannot be kept out of the daily life.
Technically speaking earphones falls in the category of transducers that convert electrical energy into sound energy.  Undoubtedly, over the years companies have been adding more and more complex features in the earphones to improve the listening experience of the users.  In this article we will explore more about the earphones.
Earphones are available in many shape, size and colors with pricing depending on quality and varying from company to company.  The above image shows a glimpse of commonly used earphones.
A connector also known as the jack is that part of the earphone which takes electrical signals from the audio output port of the devices like mobile phones, laptop, computers, music player etc.  It is manually connected and set in the audio output port of the device.  There are three contact areas known as the TIP, RING and the Sleeve as shown in the image above and therefore this connector is also called as TRS connector.

The housing is made up of rubber and is designed to give a good grip while connecting and disconnecting the connectors. The housing encloses the wires soldered to the contacts as shown in the above image.

There are three wires each soldered to one of the metal contact of the jack. One wire is for ground, and the other two corresponding to the left and the right earphone.

The above image shows the junction from where wires get distributed to the left and right ear piece. Each ear piece has two wires out of which one is common/ground. The other carries the electrical signal for the respective ear piece.

The above image shows the tip and the filter. Tip also known as ear tip is that part of the earphone which makes contacts with the ear. The circular shaped tip is made up of silicone.  It holds the earpiece in the ears and therefore needs to be soft and comfortable.

The job of the filter is to protect the earwax and other dust particles from entering into the earpiece which in turn spoils the sound quality.

 

Removing the back casing we can see the wires soldered to the driver unit of the earphone which in turn are connected to the voice coil.

 

Under the filter is the diaphragm made up of a thin film of plastic. It is the motion of the diaphragm which produces vibration of the surrounding air particles thereby producing sound. The vibration is dependent on the electrical signal from the device.

 

Diaphragm is connected to the voice coil and is placed in the slot surrounding the permanent magnet.  The voice coil receives the analog audio signals and behaves as electromagnet. The resultant force produced by the two magnetic fields causes the diaphragm to vibrate, thus producing sound.

 

The filter consists of two parts. A metal jacket and a metallic grill sheet. The metal jacket is the outermost part of the earphone from where the sound enters the ear. Both the metal jacket and the grill sheet serves the same purpose of protecting internal audio components from outside particles like ear wax and dust. The design of the grill sheet is very important as it needs to provide a clear passage for the sound. Sound quality is highly dependent on the grill sheet