½-inch Infrasound Microphone, Prepolarized

Infrasound Microphone Cartridge Type 4964 is designed for high-precision, acoustic measurements where an infrasound microphone with high sensitivity is required. Being prepolarized, Type 4964 can be used with both CCLD and classical preamplifiers, and makes the microphone especially well-suited for battery operated equipment and operation in environments with high humidity.

USE SCENARIOS

• General noise measurements
• Wind turbine measurements
• Sonic boom measurements

INFRASOUND AND FREE-FIELD RESPONSE

At infrasound and frequencies below a few kHz, the pressure and free-field response are the same. At higher frequencies, reflections and diffractions cause pressure to increase in front of a microphone's diaphragm.

Type 4964 has been optimized for free-field, and designed for use with the protection grid in place. Type 4964 is also suited for use in class 1 sound level meters and for all high-precision acoustic measurements where a robust and stable free-field microphone with an upper frequency of 20 kHz is required.

BUILD AND STABILITY

A press-fitted, stainless-steel diaphragm ensures superior longterm stability and mechanical robustness – Type 4964 will withstand the 1 m drop test of IEC 60068–2–32.

INDIVIDUAL CALIBRATION  

As all Brüel & Kjær microphones, each Type 4964 is provided with an individual calibration chart including information about the open-circuit sensitivity, the frequency response in a free field as well as the electrostatic actuator response. Using the calibration data and the REq-X feature of LAN-XI, a real-time correction for different measurement situations can increase accuracy.