& Microphone Elements > Technical Notes Regarding Microphone Elements
Dynamic microphone elements use magnetic elements that convert sound into small electrical signals in a manner that is basically the reverse of that used by loudspeakers to convert electrical energy into sound. Dynamic microphones are rugged, reliable, and have a "warm" sound quality desirable to many vocalists.
Electret condenser microphones use an element with a thin membrane (diaphragm) connected to an electronic circuit. Membrane motion caused by sound pressure is sensed by the electronic circuit and converted into a usable electrical signal. Condenser microphones have smooth, extended frequency response and a clarity and definition not usually found in dynamic microphones. They can also be miniaturized, making them especially suitable for clip-on use.
Both dynamic and electret condenser microphones can be designed to be directional or omnidirectional. Directional microphones receive sound more efficiently from one direction than from others. This is useful when it is desired to pick up sound from greater distances or to de-emphasize unwanted external sounds. Omnidirectional microphones receive sound equally well from all directions. This is desirable in many situations, such as for clip-on microphones which cannot be directly in front of the mouth.
Handheld transmitters almost always use directional vocal microphones, which may be either dynamic or condenser. In many cases, a particular wireless system is only available with one type of handheld transmitter and one type of microphone element, usually dynamic. More expensive systems may offer a choice of either dynamic or condenser elements. Dynamic microphone elements tend to sound warmer and more mellow; condenser elements tend to have a wider and smoother frequency response and greater clarity.
For body-worn microphones, the most popular choice is a clip-on (lavalier) microphone, which may be either directional or omnidirectional. Because electret condenser microphone elements can be made considerably smaller than dynamic microphones, no modern clip-on microphones have dynamic elements. Omnidirectional clip-on microphones are smaller and usually less expensive than similar directional units.
Omnidirectional clip-on microphones work well in most situations and are more popular than directional types. Except when external noise is a problem, this type of microphone is easy to use and provides excellent sound quality. Directional clip-on microphones are useful where feedback is a potential problem, where the external noise level is high or where reverberation and echo are troublesome. However, they tend to change in sound quality and level if the wearer turns his or her head away.
A head-worn microphone can provide excellent rejection of external noise without the drawbacks of ordinary directional microphones. A directional element is normally used in head-worn microphones, providing good rejection of external noise. The microphone is also close to the mouth, allowing the gain to be turned down, further reducing outside noise. In addition, because the microphone is attached to the head, instead of some location on the chest, the sound quality does not change as the user's head turns.
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