The humble microphone has come a long way since its first inception as a mechanical device. So, what is the real purpose of a microphone? It is fairly obvious the modern-day mike is utilized so a voice / sound can be heard louder than its original form. The new technology wishes to take varying pressure waves that are in the air and then convert them into an electrical signal. In this blog we look at the technologies available to do this.
Fiber Optic technology uses very thin cables of glass to transmit data rather than copper cables. This technology means that unlike conventional mikes, the size can be reduced dramatically as no copper is used. This means that they can be used in a manner of sensitive equipment, or perhaps in areas that have a lot of electrical distortion. The whole microphone can be made without any metal whatsoever, which means they can be of use in MRI applications where RF interference can be an issue.
The dynamic microphone utilizes electromagnetic technology. This is when a magnet travels around a coil of wire, this induces a current in the wire. So, in a microphone using this technology a diaphragm moves when the sound waves hit it creating a current.
Electret are the most commonly used microphones on the planet, they are also probably the cheapest. This type of microphone is used in computers, mobile phones and headsets. In a way the electret is a type of condenser microphone so the electrical charge is replaced with electret material.
A ribbon microphone has the advantage that both sides of the mike can pick up any sound, this is achieved by a thin metal ribbon is suspended in a magnetic field. When the ribbon is moved by sound waves the current changes through it.
A very popular microphone with artists and stage performers, the condenser microphone is basically a capacitor. One of the capacitor’s plates move when hit by sound, this then changes the capacitance and a signal can then be amplified. The one drawback with this type of mike is that a small battery is required to supply the capacitor with some voltage.
Certain crystals have the property of being able to change their shape and at the same time their electrical properties, this is exactly how a Quartz watch works. If you attach a diaphragm to the crystal then it will create a signal when the diaphragm is hit by sound waves.
Cardioid microphones are commonly used in recording live performances as little interference from behind the mike will be picked up. This means that the audience will not be heard and the person directly in front of the mike will be picked up the best. There is a sweet spot in the center of the microphone that is perfect for picking up sounds directly in front of the microphone. These microphone technologies differ greatly but there is one common thread and that is the diaphragm which converts the sound waves into an electrical signal.