KEY REGIONAL COMPARISON COOMET.AUV.A-K5. ANALYSIS OF THE RESULTS

The  article  analyzes  the  results  of  bilateral  key  regional  comparison  COOMET.AUV.A-K.5  related  to  the calibration of  one-inch  laboratory  standard microphones  in  the  frequency  range  from 2 Hz  to 10 kHz. The national metrology institutes in the field of acoustics of: Ukraine (DP NDI “Systema”) and Poland (GUM) have been participated in this comparison. The participants are presented the measurement results of the level and phase of the pressure sensitivity, as well as corresponding expanded uncertainty of measurements for the one-inch laboratory standard microphone, which in this case perform functions of the carrier-standard. On the basis of the obtained data, the stages of equivalence of the measurement results of DP NDI “Systema” were calculated in relation to the corresponding reference values, obtained during the key comparison of Consultative Committee for  Acoustics,  Ultrasound  and  Vibration  of  the  International  Bureau  of Measures  and  Pounds  –  CCAUV.A-K5;  it  has  been established that they are equivalent within the uncertainties declared by the participants. 

However,  several  comments  were  raised  during  by  international  experts  while  reviewing  the  obtained  results.  These comments mainly concern the effect of rather high measurement uncertainty of the pilot laboratory on the comparison results. The followed  discussion  revealed  that  the  equivalence  of  the  results of DP NDI  “Systema”  and CCAUV.A-K5  can  be  definitively established  for  all  frequencies,  excepting  frequency  2  Hz  while  measuring  the  sensitivity  level,  and  for  all  frequencies,  but excluding the range 2– 4 kHz while measuring the sensitivity phase. For measurements at frequencies where it was impossible to reach  an  unambiguous  conclusion  on  the  equivalence  of  the  obtained  results,  it  was  recommended  to  increase  the  declared uncertainty of measurements.