Technology: Your ‘mic’ and how it works

All the different sounds that we hear are caused by minute pressure differences in the air around us. What’s amazing is that the air transmits those pressure changes so accurately over relatively long distances. This will cause an electrical current in the microphone to vary, at which it is sent out to a mixer, preamplifier or amplifier for use. Microphones just convert a real sound wave into an electrical audio signal. Jean-Claude Gatete, an electronic appliance salesman, says that microphones are considered unique not because of the technology involved, but more importantly, what they are designed for. All modern microphones are trying to accomplish the same thing as the original, but do it electronically rather than mechanically. A microphone takes varying pressure waves in the air and converts them into varying electrical signals. Carbon microphones These are the oldest and simplest microphone. It has a thin metal or plastic diaphragm on one side. As sound waves hit the diaphragm, they compress the carbon dust, which changes its resistance thus changing the amount of current that flows. Dynamic microphones These take advantage of electromagnet effects where the diaphragm moves either a magnet or a wire when sound waves hit the diaphragm, and the movement creates a small current. They have hardy diaphragms, but are damaged when the suspension wires break due to dropping. They are very strong and some give a very clean and sensitive sound. And because of their durability, they are usually used in live performances, where mic dropping is common. Ribbon microphones These are very rare and only used in the best recording studios. They are very sensitive to shock and large sound volumes, and easily damaged. Sound waves move the ribbon which changes the current flowing through it. Condenser microphones Their development has been partially incited by the development of digital recording. As standards for recording improved, the quality of recording microphones had to improve to keep pace. They tend to record sound as it really is, meaning the vocalists must be really good. Wireless Very visible in karaoke and stage performances, wireless mics can be both convenient and the reverse (due to batteries needed, and interference from outside sources). They are essentially the same as ordinary microphones. The transmitter can be in the body of a handheld mic. They have two antennae on the receiver end putting out a level signal for the mixer. When the signal strength between the two antennae varies, the receiver will opt for the stronger signal. True diversity wireless systems are usually far less sensitive to interference than single-antennae systems. Lavaliere Mics This is the familiar ‘interviewer’s collar pin’ worn at the chest, clipped to clothing. These can either be corded or wireless. The wireless version runs into a transmitter, usually worn on the belt. Contact: eddiemukaaya@yahoo.com