Microphone

The microphone is a mechanism using to transfer the sound energy into the electrical energy. Sound is propagated through a medium such as air by means of wave motion. Sound pressure level is the incremental variation from the static pressure in the air absent a sound wave. A microphone typically includes a surface called a diaphragm which vibrates in response to sound waves incident thereon. The diaphragm is coupled to circuitry which translates the diaphragm vibrations into electrical signals which are proportional to the sound waves. Microphones employ transducers, such as dynamic transducers, condenser transducers, electret transducers, solid state transducers, and other types of transducers, to convert impinging sound energy into electrical signals which can be amplified and broadcast to an audience or applied to recording equipment to record a performance. Usually, there are dynamic microphone, condenser microphone, piezoelectric/piezoresistive microphone and electret condenser microphone. A dynamic microphone includes a moving coil transducer to convert the movement of a pole into electrical energy. The dynamic microphone is typically designed for a set or fixed acoustic frequency range and therefore, requires substantial mechanical retrofitting or resizing to alter its acoustic frequency range response. An electret microphone contains a preamplifier, typically a field effect transistor (FET), and voice is converted to electrical signal by capacitance. Changes in the air pressure cause changes to the capacitance between a conductive plate and a conductive polarized foil. Electret microphones are commonly used in headsets for telephony, computer telephony and speech recognition applications. Such electrets have virtually displaced the larger, heavier dynamic microphones. Condenser microphones are a type of microphone having a very flat frequency response, low noise, and low cost. These characteristics make condenser microphones the logical choice for applications requiring miniature microphones, such as hearing aids, mobile telephones and digital voice recorders. Electret condenser microphones typically include a diaphragm and ring assembly, a backplate, and a spacing washer separating the diaphragm and ring assembly from the backplate. They also include an FET mounted on a printed circuit board. Unidirectional electret condenser microphones typically include a housing, a diaphragm and a ring assembly, a backplate, and a spacer separating the diaphragm and ring assembly from the backplate. A directional microphone is a microphone system having a directivity pattern. Known directional patterns are spherical or omnidirectional, figure-of-eight or bidirectional, cardioid, supercardioid, hypercardioid and lobe pattern. An omnidirectional microphone is a microphone with an even or equal response sensitivity to sound from all directions over a full 360 degree range. A cardioid microphone is a microphone having a heart-shaped direction response pattern resembling a graph of a mathematical cardioid function. A supercardioid microphone has a direction response pattern more attenuated for sounds arriving from a side direction than a cardioid direction response pattern. Wireless microphones provide freedom of movement by eliminating the audio cable which has traditionally been used with hand held microphones. This results in enhancing the performance visually and minimizing staging problems. A wireless microphone typically operates as a radio transmitter which delivers VHF signals to a receiver. Power is supplied by a battery. The internal components, including those relating to audio and radio frequency, are placed on a single circuit board which is located within the microphone housing.