TYPE 4964

½-inch Infrasound Microphone, Prepolarized

Infrasound microphone specifically designed for high-precision, acoustic measurements with high sensitivity in the frequency range of 0.02 Hz to 20 kHz.

見積もり依頼

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.

Capacitance
14 pF
Diameter
0.52
Dyn. range
14.6 – 146 dB
Freq. range
.02 – 20000 Hz
Inherent noise
14.2 dB A
Lower limiting frequency -3dB
0.02 Hz
Optimised
Free field
Polarization
Prepolarized
Polarization voltages
0 V
Pressure coefficient
-0.01 dB/kPa
Sensitivity
50 mV/Pa
Standards
IEC 61094-4 WS2F
Temperature coefficient
-0.006 db/ºC
Temperature range
-30 – 150 C
Venting
Rear
Weight
gram
Sound field
Free-field
Input type
CCLD IEPE
Microphone type
Free field