4227 – Mouth Simulator

A stable sound source for the testing of acoustic transducers

Brüel & Kjær Mouth Simulator Type 4227 is a stable, low distortion sound source used for the testing of acoustic transducers. When testing telephone transmitters and close talking microphones it is required that the sound field closely replicates the sound field generated by the human mouth, as specified in IEEE 269. Type 4227 fulfills this requirement. Calibration of 4227 can be made with the aid of the Calibration Jig UA 0901 provided.

The jig is designed to hold a 1/2″ measuring microphone at a distance of 25 mm from the lip ring (see Fig. 1.). It consists of two interlocking plates which can be fitted together in two ways enabling the microphone to be held with its axis at either 0° or 90° to the mouth axis.

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Features of Type 4227 – Mouth Simulator


  • Quality control testing of frequency response and distortion of telephone transmitters and closetalking microphones
  • Sound source for acoustic measurements


  • Accurate simulation of human voice field
  • Continuous SPL of 110 dB at 25 mm from lip ring
  • Low distortion
  • Built-in overload protection circuit
  • Optional regulating microphone for very accurate frequency response control
  • Calibration Jig included
  • Conforms to Standards: IEEE 269, 661 and ITU-T Rec. P.51

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4227 – Mouth Simulator

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