G.R.A.S. 44AA Mouth Simulator according to ITU-T Rec. P51 with built-in power amplifier

ITU-T rec.: P.51
Special feature: Built-in power amplifier
  • 44AA Mouth Sim ITU-T P51, power amp
  • 44AA Mouth Sim ITU-T P51, power amp

At the mouth reference point (MRP), which is 25mm from the detachable lip ring (35mm from the mouth of the G.R.A.S. 44AA), the maximum continuous signal it can produce in 1/3-octave bands is 100dB re. 20µPa in the frequency range 100Hz to 16kHz. Its loudspeaker accepts an external signal either directly or via its own built-in power amplifier (when power is applied).

Jigs are included for calibration according to CCITT P.51 and IEEE 269. These are for use with 1/4" or 1/2" microphones. One jig holds the microphone at 0º incidence (1/4" only) to the sound source, the other at 90º incidence (1/4" or 1/2").

Connector type BNC
ITU-T recommondations P.51
IEEE standard 269, 661
Input impedance 20
Maximum power, continuous W 10
Maximum power, pulsed 2 sec. W 50
Temperature range, operation °C / °F 10 to 35 / 50 to 95
Gain dB 10
Input signal, max. Vrms 2
CE/RoHS compliant/WEEE registered Yes/Yes/Yes
Weight g / oz 1050 / 37.038

Built-in power amplifier

Maximum continuous output level at MRP [200 Hz - 6 kHz] 110 dB re. 20 μPa

Maximum continuous output level at MRP [100 Hz - 16 kHz] 100 dB re. 20 μPa

Distortion 250 Hz - 8 kHz (Linear signal @ 94 dB at MRP) typically 1 %, max. 1.5 %

Frequency response


G.R.A.S. RA0104 Jig (CCITT P51)
G.R.A.S. RA0105 Jig (IEEE 269)


G.R.A.S. RA0110 Conical mouthpiece