Larson Davis SoundTrack LxT, Руководство пользователя

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16 Glossary and Formulas LxT Manual
Microphone Guidelines
Microphone Types : A device for detecting the presence of
sound. Most often it converts the changing pressure
associated with sound into an electrical voltage. It can be
composed of one of the following types:
Capacitor (Condenser): A microphone that uses the motion
of a thin diaphragm caused by the sound to change the
capacitance of an electrical circuit and thereby to create a
signal.
Prepolarized: A microphone that uses the motion of a thin
diaphragm caused by the sound to change the capacitance of
an electrical circuit and thereby to create a signal. The
voltage across the diaphragm is caused by the charge
embedded in the electric material so no external source is
needed.
Microphone Uses : The frequency response of microphones
can be adjusted to be used in specific applications. Among
those used are:
Frontal incidence (Free Field) : The microphone has been
adjusted to have an optimally flat frequency response when
in a space optimally free of reflections and when pointed at
the source of the sound.
Random incidence: The microphone has been adjusted to
have an optimally flat frequency response for sound waves
impinging on the microphone from all directions.
Pressure: The microphone has not been adjusted to have an
essentially flat frequency response for sound waves
impinging on the microphone from all directions.
What a microphone measures : A microphone detects more
than just sound. The motion of a microphone diaphragm is
in response to a force acting on it. The force can be caused
by a number of sources only one of which are we interested:
sound. Non-sound forces are: (1) direct physical contact
such as that with a finger or a raindrop; (2) those caused by
the movement of air over the diaphragm such as
environmental wind or blowing; (3) those caused by
vibration of the microphone housing; and (4) those caused
by strong electrostatic fields.