LESSON 3
DEFINE AUDIO MICROPHONE CIRCUITS
TASK
Describe the uses and operation of four types of microphones and related circuits.
CONDITIONS
Given information and illustrations on the operation and circuitry of four types of
microphones.
STANDARDS
Demonstrate competency task skill and knowledge by responding to the multiple
choice test covering audio microphone circuitry of the four types of microphones;
carbon, ceramic, dynamic and cardioid.
Learning Event 1:
DESCRIBE USES AND OPERATION OF A CARBON MICROPHONE
1. Microphones. Microphones may be classified according to their physical
design, such as carbon, capacitor, ribbonvelocity, moving coil, semiconductor and
ceramic. Special use microphones such as dual, inline, and high intensity
microphones will also be discussed in this lesson.
2. What is a microphone? A microphone is a device which converts acoustical
energy into electrical energy. Microphones can be also called an electroacoustic
transducer.
3. Basic Principles of Microphone Operation. Microphones are divided into two
categories of operation; velocity and pressure.
a. Pressureoperated microphones employ a diaphragm with only one surface
exposed to the sound source. The displacement of the diaphragm is proportional to
the instantaneous pressure of the sound wave. At lower frequencies such
microphones are practically nondirectional.
b. A velocity microphone is one in which the electrical response corresponds
closely to the sound input. A velocity microphone can also be called a gradient
microphone. A gradient microphone is a microphone that corresponds to the gradient
of sound pressure exerted upon it.
4. Polar Field Patterns. A polar field pattern is a plot employing polar
coordinates, showing the magnitude of sound quality in some or all directions from
a given point for 360 degrees. Polar plots are used to present the direc
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