Abstract | The tube method for specific acoustic impedance measurements is well known. In this report an iterative scheme is presented that is based on the exact plane-wave analysis of the standing-wave pattern in the tube. To use the method in its proposed format, the tube attenuation coefficient is assumed known either from theoretical prediction or prior experimental determination. The speed of sound can be calculated if the temperature of the air in the tube is measured. Alternatively, the wavelength can be measured directly by measuring the distance between two minima in the tube. Two sound pressure measurements, at the minimum and one other point, are then all that is required. |
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