TYPE 4949

Surface Microphone For  Automotive Applications 

Automotive surface microphone designed for measurement of the true surface pressure. Ideal for mounting directly on the car surface during wind-tunnel tests and for measuring in confined spaces.

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Type 4949 is designed for measuring the true surface pressure on a car (in automotive applications). The microphone is exceptionally suited for mounting directly on the car surface during wind-tunnel tests or for measurement in confined spaces; for example, on the firewall or the underside of a vehicle.

USE SCENARIOS

  • Noise measurement on surfaces including glass and in confined spaces
  • Wind-tunnel testing
  • Low to medium noise measurements
  • Flush mounting
  • Connects to CCLD input

The optional mounting pads allow easy mounting of the microphone even on the curved surfaces of a car. Despite its small size, Type 4949 is a rugged and stable measurement microphone. The microphone housing and the metallic parts of the diaphragm-backplate arrangement, including the diaphragm, are all titanium, ensuring uniquely high resistance to corrosion.

The diaphragm is flush with the microphone housing in order to minimize the wind-generated noise of the microphone. The microphone pressure-equalization vent is placed just next to the diaphragm on the front of the microphone. This is important since the static pressure can vary rapidly with position when the microphone is exposed to turbulent pressure fluctuations.

Surface Microphone Type 4949 has a built-in preamplifier for connection to CCLD inputs. The sensitivity of the microphone is optimized in order to achieve a good noise floor and still allow measurements at higher levels without clipping.

The microphone supports IEEE 1451.4 (TEDS) for remote identification of the transducer and reading of its calibrated sensitivity. Type 4949 B also supports Brüel & Kjær’s proprietary Charge Injection Calibration (CIC) for remote verification of the complete, calibrated measurement channel.

Surface Microphone Type 4949 is yet another product based on Brüel & Kjær’s new patent-pending microphone technology.

With this technology, it is possible to obtain the same high
stability and uniformity as that of the traditional and well-known Brüel & Kjær measurement microphones.

Capacitance
pF
Diameter
1/2
Dynamic range
30 – 140 dB
Frequency range
5 – 20000 Hz
Inherent noise
30 dB A
Lower limiting frequency -3dB
5 Hz
Optimised
Surface
Polarization
Prepolarized
Polarization voltages
V
Pressure coefficient
-0.007 dB/kPa
Sensitivity
11.2 mV/Pa
Temperature coefficient
0.013 db/ºC
Temperature range
-30 – 100 C
Venting
Front
Weight
gram
Sound field
Special
Input type
CCLD IEPE
Microphone type
Surface