Uncertainty analysis of the two-microphone method

Development of Impedance Tube to Measure Sound Absorption Coefficient

“…They also stated the errors were minimized by decreasing the tube length, having a non-reflective source end and keeping the microphone as close as possible. The frequency also depends on complex reflection and normalized acoustic impedance were investigated in a verified systematic work [9]. Cho and Nelson [10], proposed improved multiple methods to measure transfer function value.…”

A systematic uncertainty analysis for liner impedance eduction technology

“…In order to get the 95 percent confidence interval results for complex-valued variables, the normal confidence interval should be extended to a confidence area for its possible correlated real and imaginary parts. For a normally distributed complex variable with a real part x R and an imaginary part x I , the confidence region is given by [24,25] x…”

“…Unfortunately these efforts did not provide a systematic method for the propagation from component uncertainties to the overall uncertainty in the identified impedance results. In contrast to the Monte Carlo method, the purpose of this paper is to provide a multivariate uncertainty analysis method [24,25], which makes it possible to track the multiple, possible correlated components. In order to avoid numerical uncertainty in this study, a straightforward single mode analysis is used.…”

“…Acoustic reflections at the leading and trailing liner boundaries Check with scattering matrix results[21] Random or bias errors from the two-microphone wave decomposition method Estimate according the suggestions in Ref [24]. …”

Estimating uncertainty of measurements for cavitation detection in a centrifugal pump

“…Also an ISO-GUM [5], revised by ISO/IEC Guide [7], predicts that in most cases, type A may be used. To evaluate the measurement uncertainty, also other methods are available [8][9][10], but they are not discussed in this paper.…”