Microphones are transducers (a device that converts one form of energy into another) that take acoustical energy (sound waves/vibrations) and convert it into electrical energy (the audio signal). The main element inside a microphone that is used in converting the energy is called the diaphragm. Different types of microphones (which I will talk about in a later blog) have different patterns for picking up sound waves, but they all have a diaphragm. The diaphragm is a thin piece of material (such as paper, plastic, silk, or aluminum) that vibrates when it is struck by sound waves. For example, below is a typical hand-held mic, called a dynamic mic, with a paper diaphragm that picks up the sound waves.
Carefully attached to the diaphragm is a copper coil wrapped around a magnet. This magnet and coil produce a magnetic field inside that microphone used to convert the sound waves into an electric audio signal. When the diaphragm receives vibrations the coil moves back and forth, over the magnet, creating an electromagnetic induction. This induction is the audio signal that is then sent to a sound board for mixing, EQ, and gain/volume control of the signal.
If you think about it, a microphone works the same as a speaker, but backwards. The microphone converts the sound waves into an electric audio signal and after it is sent through a sound board, the signal is boosted by way of an amplifier and then sent to a speaker that converts the electric audio signal back into sound waves. Here is an example of a speaker diaphragm which looks a lot like the inside of a mic, but beefed up a lot more and reversed.
Now the next time you go to an event with a PA system you will have a better understanding of the 'magic' of the microphone. Feel free to explain it to your nieghbor sitting next to you.
*Don't forget to let me know what you think by leaving a comment below.
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