Evaluation of a multi-point method for determining acoustic impedance

A multipoint method for determining acoustic impedance was evaluated in comparison with the traditional standing wave and two-microphone methods using 30 test samples covering the reflection factor magnitude range 0.004-0.999. The multipoint method is shown to combine the strengths of the standing wave and two-microphone methods while avoiding some of their inherent weaknesses. In particular, the results obtained suggest that the multipoint method will be less subject to flow induced random error than the two-microphone method in the presence of significant broadband noise levels associated with mean flow.