This Low Noise Microphone is designed for sound power measurements and free-field measurements in strong magnetic fields, over a frequency range of 5 Hz to 20 kHz.

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Low Noise Microphone Type 4955 consists of a high sensitivity ½” cartridge, which has been optimised for the lowest inherent noise.

Type 4955 TEDS microphone has a noise floor typically less than 5.5 dB (A), hence allowing measurements well below 10 dB(A).


  • Sound power measurements
  • Low-level measurements
  • In-cabin measurements
  • Measurements in strong magnetic fields
  • Homeland security applications

Although standard 1″ and ½″ microphone solutions adequately cover the majority of noise measurements under IEC, ISO and ANSI standards, there is an increasing need for measurements below the noise floor of the standard solutions.

In these cases, Brüel & Kjær’s Type 4955 Low Noise Microphone is the optimal choice. A ½″ all-titanium, noise-optimised microphone cartridge with laserwelded diaphragm, is combined with a low-noise preamplifier with 20 dB gain.

The result is a system with low noise, high sensitivity, excellent long-term stability and outstanding corrosion resistance.

Type 4955-A is a special version optimised for use with Brüel & Kjær Hand-held Sound Level Meters / Analyzers Type 2250 and 2270.

Dyn. range6.5 – 110dB
Freq. range10 – 16000 Hz
Inherent noise6.5 dB A
Lower limiting frequency – 3dB10 Hz
OptimisedLow Noise
PolarizationExt polarized
Polarization voltages200 V
Pressure coefficient-0.013 dB/kPa
Sensitivity1100 mV/Pa
Temperature coefficient-0.01 dB/°C
Temperature range-20-100 °C
Weight34 gram
Sound fieldFree-field
Input typeClassic
Microphone typeLow Noise