An acoustical-electrical transducer by which sound waves in air may be converted to electrical signals.

Acoustic Feedback

Unwanted interaction between the output and input of an acoustical system, e.g., between the loudspeaker and the microphone of a system.

Bias Voltage

A low DC voltage typically supplied by a body-pack wireless transmitter to power a condenser microphone.

Boundary Microphone

A type of microphone that detects sound pressure level changes at a boundary of the acoustic space in order to reduce interference between direct and reflected sound.


The portion of a microphone that converts acoustic energy to electrical energy.


Describes the pickup pattern of one type of directional microphone, which is roughly in the shape of a heart. Such microphones are several dB less sensitive to sound arriving from sources at angles 90 degrees or greater away from its front.


The surface that vibrates in response to sound.

Distance Factor

Provides an indication of a directional microphone′s increased working distance, compared to a DF of 1.0 for an omnidirectional mic.

EES (Early Early Sound)

Structure-borne sound may reach the microphone in a room before the airborne sound because sound travels faster through the denser materials.


A microphone has positive polarity if a positive pressure on its diaphragm results in a positive output voltage.

Proximity Effect

An increase in the bass response of some mics as the distance between the mic and its sound source is decreased.

Self Noise

Microphone inherent self-noise is usually specified as the equivalent Sound Pressure Level (SPL) which would give the same output voltage, with typical values being 15-20 dB SPL.


A porous device used to cover the microphone of a sound level measurement system which is designed to minimize the effects of winds and wind gusts on the sound levels being measured. Typically made of open cell polyurethane foam and spherically shaped.

See also: Acoustic Calibrator, Acoustics, Audio Transducer, Boundary Microphone, Capacitor Microphone, Carbon Microphone, Condenser Microphone, Distance Factor, Dynamic Microphone, Early Early Sound, Polarity, Pop, Self Noise.

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Subjects: Instrumentation Noise & Vibration

Bruel & Kjaer - Technical Reviews These documents give detailed articles on measurement and signal processing theory.