Microphone

The 21st century cannot be imagined without mobile phones. We call anyone we want on the mobile and even if they are a thousand miles away, they can hear every word that we say, and we can hear every word that they say. We have microphones to thank for it. A microphone is an audio device which detects sound and converts it into electrical signals. Microphones can amplify the sound, i.e., increase its amplitude so that the sound can be heard over long distances by a large group of people. The types and uses of microphones are endless in today’s age, and they will all be covered here in detail. 

Working Mechanism of a Mic

A microphone has a simple working mechanism, much like the working of a human ear. The sound travels in waves. When we say something, the air particles around our mouth get energy, vibrating about their mean position. They collide with their surrounding air particles, which collide with their surrounding air particles.

Now, in a microphone, there is a diaphragm attached which vibrates due to the collision of a sound wave. There is a magnetic coil directly connected to the diaphragm in the mic. As the diaphragm vibrates, the coil moves back and forth in the presence of a magnetic field. Now, applying the basic principle of physics here, we know that electricity is produced if a coil moves back and forth in a magnetic field. 

This electric signal is then transferred to an amplifier or to a recording device, from where it is further transmitted.

Types of Microphone

1. Dynamic microphone: It is the simplest kind of microphone whose working principle is the same as described above. Due to its operating mechanism, it is also called a moving coil microphone. These microphones are highly durable and inexpensive. They are widely used on stages for public speaking. They have an added advantage of low background noise, arising from their compact construction.
   Dynamic microphones are highly directional, meaning that they pick up sound from one direction (mostly coming from the front direction of the diaphragm). Their use is widespread due to their multiple advantages, especially their robustness.

2. Condenser mic or capacitor mic: These microphones work on the principle of capacitance, which can be defined as the ability of a metal plate to hold an electrical charge. In such a mic, the diaphragm (generally consisting of gold-sputtered mylar) is close to the metal plate. As the diaphragm moves from its mean position, its distance from the metal plate also changes, altering the capacitance. These mics have a low mass, allowing them to capture changes in the sound wave very quickly.

3. Ribbon mic or velocity mic: The working principle of these microphones is somewhat similar to that of a dynamic microphone. A corrugated ribbon (made up of aluminium alloy due to its low mass) moves with respect to the permanent magnet when sound waves interact with it. A voltage is created on the ribbon. They are used in studios where low noise is needed.

Carbon and crystal mics are the other two types of microphones, but they are not used very widely.

Bluetooth Microphone

Bluetooth microphones or wireless microphones have the same working principle as a wired mic. The difference is that the transmitter lies inside the mic in the case of wireless mics. A transmitter is a unit that converts sound into a signal that can be carried over a significant distance. The working of a Bluetooth mic follows the following steps:

1. Audio is transferred to the transmitter

2. The transmitter carries the audio through radio waves

3. The receiver receives these radio waves and decodes the audio message

These microphones are advantageous as they allow higher mobility without wires connected. Also, the signal in these mics is somewhat clearer because it does not travel through cables.

However, there are drawbacks too. These Bluetooth microphones need to be charged at regular intervals, without which they cease to function. Also, since they rely on radio wave frequency to operate, there are high chances of interference by radio waves. Hence, the actual audio message can be intercepted.

Conclusion

The uses of the microphone are too many. They are used in mobile phones, computers and laptops to transfer audio messages from one point to another. They are used to amplify the sound signal so that the audio can be heard over a significant distance. Careful choice of mic can help to eliminate noise as well. Their working principle is said to be the complete reverse of loudspeakers. In a loudspeaker, the electrical signal is converted into audio as electric current flows through a coil wrapped around a magnet. This generates a magnetic field inside the loudspeaker, due to which the coil starts moving. The coil is attached to a diaphragm that moves with the coil’s movement and produces sound.