video corpo

measurement microphone / externally-polarized / free-field / 1/2"
4191 Bruel and Kjaer



  • Applications:


  • Technology:


  • Other characteristics:

    free-field, 1/2"


Designed for high-precision, free-field measurements where a 40 kHz bandwidth is required.
Type 4191 is designed for high-precision, free-field measurements where a wide bandwidth is required. Being externally polarized, Type 4191 must be used with a classical preamplifier.

Precision measurements to 40 kHz
Premium class sound level meters
Equipment complying with IEC 61672 class 1


At higher frequencies reflections and diffractions causes a pressure increase in front of the diaphragm of a microphone. If not corrected for, this would result in an increased output voltage. A free-field optimisation means that the frequency response of the microphone has been designed in such a way that the free-field response at 0 degrees incidence is flat. This microphone is optimised for use with the protection grid in place.

Free-field microphones are commonly used for sound measurement in an anechoic chamber or far away from reflecting buildings, etc. Another area for free-field microphones is for general electroacoustic measurements like loudspeaker and microphone measurements.

With an upper frequency of 40 kHz, Type 4191 is especially suited all high-precision electroacoustic measurements as well as general acoustic measurements where a robust and stable free-field microphone is required. Despite the 40 kHz upper frequency, this microphone is optimised to operate with the protection grid in place.

A press-fitted, stainless-steel diaphragm ensures superior long-term stability and mechanical robustness – Type 4191 will withstand the 1 m drop test of IEC 60068-2-32.

Other Bruel and Kjaer products

Acoustic Transducers