The Bruel and Kjaer 4227 is an accurate reference sound source developed for near field testing of telephone transmitters and microphones. It provides a standardised and realistic simulation of the human voice field.
Conforms to IEEE-269, IEEE-661 and ITU-T P.51
Accurate level and frequency response calibration is easily done using a Bruel & Kjaer ½" microphone placed in the supplied calibration jig
Accurate simulation of human voice field
Quality control testing of frequency response and distortion of telephone transmitters and close-talking microphones
Continuous SPL of 100dB 25mm from lip ring
Low distortion
Built-in overload protection circuit
At 25mm from lip ring, 20mm diameter Mouth Opening, Low-distortion sound source used for testing acoustic transducers
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